diff --git a/front/public/locales/en/operational-studies.json b/front/public/locales/en/operational-studies.json
index dd17bc0cbe6..725c48a9dac 100644
--- a/front/public/locales/en/operational-studies.json
+++ b/front/public/locales/en/operational-studies.json
@@ -426,6 +426,7 @@
       "moveLocationOnMap": "Move location on the map",
       "movePointOnMap": "Move this waypoint using the map",
       "next": "Next",
+      "noComputation": "there will be no computation for this train",
       "opId": "Operational point identifier",
       "opName": "Operational point name",
       "opType": "Type",
diff --git a/front/public/locales/fr/operational-studies.json b/front/public/locales/fr/operational-studies.json
index f63f47f1d3b..4c086fe57ba 100644
--- a/front/public/locales/fr/operational-studies.json
+++ b/front/public/locales/fr/operational-studies.json
@@ -426,6 +426,7 @@
       "moveLocationOnMap": "Déplacer le point remarquable sur la carte",
       "movePointOnMap": "Déplacez ce point en utilisant la carte",
       "next": "Suivant",
+      "noComputation": "il n'y aura pas de calcul pour ce train",
       "opId": "Identifiant de point",
       "opName": "Nom du point remarquable",
       "opType": "Type",
diff --git a/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/ItineraryModal.tsx b/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/ItineraryModal.tsx
index 54258d06365..2f90a04bec8 100644
--- a/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/ItineraryModal.tsx
+++ b/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/ItineraryModal.tsx
@@ -18,6 +18,7 @@ import type {
   PathItemLocation,
   TrainCategory,
 } from 'common/api/osrdEditoastApi';
+import { osrdEditoastApi } from 'common/api/osrdEditoastApi';
 import Banner from 'common/Banner';
 import { computeBBoxViewport } from 'common/Map/WarpedMap/core/helpers';
 import { useInfraID } from 'common/osrdContext';
@@ -35,7 +36,7 @@ import {
   getPathSteps,
   getRollingStockName,
 } from 'reducers/osrdconf/operationalStudiesConf/selectors';
-import type { PathStep, PathStepMetadata, PathStepV2 } from 'reducers/osrdconf/types';
+import type { PathStep, PathStepMetadata, PathStepV2, TrainScheduleToEditData } from 'reducers/osrdconf/types';
 import { useAppDispatch } from 'store';
 import { addElementAtIndex } from 'utils/array';
 import { Duration } from 'utils/duration';
@@ -61,6 +62,7 @@ type ItineraryModalProps = {
   itineraryModalIsOpen: boolean;
   setItineraryModalIsOpen: (isOpen: boolean) => void;
   displayTrainScheduleManagement: string;
+  trainScheduleToEditData?: TrainScheduleToEditData;
 };
 
 export type ItineraryModalFormState = {
@@ -75,6 +77,7 @@ const ItineraryModal = ({
   itineraryModalIsOpen,
   setItineraryModalIsOpen,
   displayTrainScheduleManagement,
+  trainScheduleToEditData,
 }: ItineraryModalProps) => {
   const { t } = useTranslation('operational-studies', {
     keyPrefix: 'manageTrainSchedule.itineraryModal',
@@ -153,6 +156,42 @@ const ItineraryModal = ({
   const { launchPathfindingV2, pathProperties, pathfindingError } = usePathfindingV2();
   const { convertFeatureClickToLocation } = useMapTrackSelection(infraId);
 
+  /**
+   * When a custom track name is added (one that doesn't exist in the OP parts),
+   * immediately update the train schedule's path via API to persist the local_track_name.  
+   */
+  const updateTrainSchedulePathTrackName = useCallback(
+    async (stepId: string, trackName: string) => {
+      if (!trainScheduleToEditData) return;
+
+      const { trainScheduleId } = trainScheduleToEditData;
+
+      // GET the current train schedule fresh from the DB to avoid overwriting anything
+      const { id: _, train_schedule_set_id: __, ...currentData } = await dispatch(
+        osrdEditoastApi.endpoints.getTrainSchedulesById.initiate(
+          { id: trainScheduleId },
+          { subscribe: false }
+        )
+      ).unwrap();
+
+      // Only update the local_track_name on the matching path step
+      await dispatch(
+        osrdEditoastApi.endpoints.putTrainSchedulesById.initiate({
+          id: trainScheduleId,
+          trainSchedule: {
+            ...currentData,
+            path: currentData.path.map((item) =>
+              item.id === stepId && item.location.type !== 'track_offset'
+                ? { ...item, location: { ...item.location, local_track_name: trackName || undefined } }
+                : item
+            ),
+          },
+        })
+      ).unwrap();
+    },
+    [dispatch, trainScheduleToEditData]
+  );
+
   const applyOperationalPointToStep = (
     stepId: string,
     suggestion: OperationalPointSuggestion,
@@ -546,12 +585,12 @@ const ItineraryModal = ({
           {rollingStockMessage && <Banner type="info" message={rollingStockMessage} />}
           {hasInvalidPathStepDisplay && (
             <div key={`invalid-op-${bannerWiggle}`}>
-              <Banner type="error" message={t('alertInvalidOP')} />
+              <Banner type="info" message={`${t('alertInvalidOP')} ${t('noComputation')}`} />
             </div>
           )}
           {!hasInvalidPathStepDisplay && pathfindingError && (
             <div key={`pathfinding-${bannerWiggle}`}>
-              <Banner type="error" message={pathfindingError} />
+              <Banner type="info" message={`${pathfindingError} ${t('noComputation')}`} />
             </div>
           )}
           {submitAttempted &&
@@ -678,6 +717,9 @@ const ItineraryModal = ({
                         })
                       );
                     }}
+                    onAddCustomTrackName={(trackName) => {
+                      updateTrainSchedulePathTrackName(pathStep.id, trackName);
+                    }}
                     onOpBlur={() => {
                       // If the user focuses out on an input with a valid op, we display the last valid op of this input (or empty)
                       const valueOnFocus = focusValueRef.current[pathStep.id];
diff --git a/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/PathStepItem.tsx b/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/PathStepItem.tsx
index 49e6b4bd597..9bfdc941f28 100644
--- a/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/PathStepItem.tsx
+++ b/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/PathStepItem.tsx
@@ -1,6 +1,6 @@
-import { useMemo } from 'react';
+import { useEffect, useMemo, useState } from 'react';
 
-import { ComboBox, Select, SegmentedControl } from '@osrd-project/ui-core';
+import { ComboBox, SegmentedControl } from '@osrd-project/ui-core';
 import {
   AddedLocation,
   AddLocation,
@@ -38,6 +38,7 @@ type PathStepProps = {
   categoryColors: CategoryColors;
   onOpInputChange: (value: string) => void;
   onTrackNameChange: (trackName: string) => void;
+  onAddCustomTrackName?: (trackName: string) => void;
   onOpFocus: () => void;
   onOpBlur: () => void;
   inputValue: string | undefined;
@@ -66,6 +67,7 @@ const PathStepItem = ({
   categoryColors,
   onOpInputChange,
   onTrackNameChange,
+  onAddCustomTrackName,
   onOpFocus,
   onOpBlur,
   inputValue,
@@ -110,11 +112,8 @@ const PathStepItem = ({
       return (message += t('requestedPoint'));
     }
 
-    const trackInfo =
-      location && location.local_track_name ? `, ${t('track')} ${location.local_track_name}` : '';
-
     if (location?.operational_point.type === 'id') {
-      return (message += t('opId') + trackInfo);
+      return (message += t('opId'));
     }
 
     const secondaryCodeInfo =
@@ -130,7 +129,7 @@ const PathStepItem = ({
       message += t('uic') + ' ' + location.operational_point.uic;
     }
 
-    return message + secondaryCodeInfo + trackInfo;
+    return message + secondaryCodeInfo;
   };
 
   const selectedSecondaryCodeOption = useMemo(() => {
@@ -169,17 +168,29 @@ const PathStepItem = ({
     return [{ label: '', id: '' }, ...sortedSuggestions];
   }, [pathStepMetadata, selectedSecondaryCodeOption.id]);
 
+  const [filteredTrackSuggestions, setFilteredTrackSuggestions] = useState(trackNameSuggestions);
+
+  useEffect(() => {
+    setFilteredTrackSuggestions(trackNameSuggestions);
+  }, [trackNameSuggestions]);
+
   const selectedTrackNameOption = useMemo(() => {
+    // When OP is invalid but has a local_track_name, show it
+    if (pathStepMetadata?.isInvalid && pathStepMetadata.localTrackName) {
+      return { label: pathStepMetadata.localTrackName, id: pathStepMetadata.localTrackName };
+    }
+
     // No track should be selected if the path step is invalid or has no secondary code
     // or is a step added by map click
-
     if (!isOpRefMetadata(pathStepMetadata) || !pathStepMetadata.trackName) {
       return EMPTY_OPTION;
     }
 
     return (
-      trackNameSuggestions.find((track) => track.label === pathStepMetadata.trackName) ||
-      EMPTY_OPTION
+      trackNameSuggestions.find((track) => track.label === pathStepMetadata.trackName) || {
+        label: pathStepMetadata.trackName,
+        id: pathStepMetadata.trackName,
+      }
     );
   }, [pathStepMetadata, trackNameSuggestions]);
 
@@ -293,6 +304,7 @@ const PathStepItem = ({
       className={cx('path-step-wrapper', {
         'is-placeholder': isTrailingPlaceHolder,
         'map-selection-active': isMapSelectionMode,
+        'is-invalid': isInvalidAndIsEditing,
       })}
     >
       <div
@@ -455,15 +467,28 @@ const PathStepItem = ({
               <div
                 className={cx('track-name', {
                   invalid: isInvalidAndIsEditing,
+                  'track-name-unknown':
+                    isOpRefMetadata(pathStepMetadata) && pathStepMetadata.isTrackNameUnknown,
                 })}
               >
-                <Select
+                <ComboBox
                   id={`pathStep-status-${pathStep.id}`}
                   value={selectedTrackNameOption}
-                  options={trackNameSuggestions}
-                  getOptionLabel={(option) => option.label}
-                  getOptionValue={(option) => option.id}
-                  onChange={(option) => onTrackNameChange(option?.label ?? '')}
+                  suggestions={filteredTrackSuggestions}
+                  getSuggestionLabel={(option) => option.label}
+                  onChange={(e) => {
+                    const input = e.target.value.toLowerCase();
+                    setFilteredTrackSuggestions(
+                      trackNameSuggestions.filter((s) => s.label.toLowerCase().includes(input))
+                    );
+                  }}
+                  onSelectSuggestion={(option) => onTrackNameChange(option?.label ?? '')}
+                  resetSuggestions={() => setFilteredTrackSuggestions(trackNameSuggestions)}
+                  allowCustomValue
+                  onAddCustomValue={(value) => {
+                    onTrackNameChange(value);
+                    onAddCustomTrackName?.(value);
+                  }}
                   small
                   narrow
                 />
diff --git a/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/hooks/usePathStepsMetadata.ts b/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/hooks/usePathStepsMetadata.ts
index 6a9b112795c..03ceb2c4728 100644
--- a/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/hooks/usePathStepsMetadata.ts
+++ b/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/hooks/usePathStepsMetadata.ts
@@ -105,19 +105,22 @@ export const usePathStepsMetadata = (
         const matchedOp = pathStepsOperationalPoints.get(pathStep.id)?.at(0);
 
         const { local_track_name } = location;
-        const isValidLocalTrackName = local_track_name
-          ? matchedOp?.parts.some((part) => {
+
+        if (!matchedOp) {
+          newPathStepsMetadataById.set(pathStep.id, {
+            isInvalid: true,
+            localTrackName: local_track_name ?? undefined,
+          });
+          return;
+        }
+
+        const isTrackNameUnknown = local_track_name
+          ? !matchedOp.parts.some((part) => {
               const track = trackSectionsById[part.track];
               if (!track) return false;
               return local_track_name === part.local_track_name;
             })
-          : true;
-
-        // If no op is found or if its local_track_name is invalid, it means the path step is invalid
-        if (!isValidLocalTrackName || !matchedOp) {
-          newPathStepsMetadataById.set(pathStep.id, { isInvalid: true });
-          return;
-        }
+          : false;
 
         const parts: Extract<PathStepMetadata, { isInvalid: false; type: 'opRef' }>['parts'] =
           matchedOp.parts.map((part) => ({
@@ -133,6 +136,7 @@ export const usePathStepsMetadata = (
           uic: matchedOp.extensions?.identifier?.uic,
           secondaryCode: matchedOp.extensions?.sncf?.ch,
           trackName: local_track_name ?? undefined,
+          isTrackNameUnknown,
           parts,
         });
       });
diff --git a/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/utils.ts b/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/utils.ts
index c014c8b3a80..ce9eaf0cbbb 100644
--- a/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/utils.ts
+++ b/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/Itinerary/utils.ts
@@ -17,7 +17,8 @@ export const computePathStepCoordinates = (pathStepMetadata: PathStepMetadata) =
     const foundPart = pathStepMetadata.parts.find(
       (part) => part.trackName === pathStepMetadata.trackName
     );
-    return foundPart ? [foundPart.coordinates] : [];
+    // If the track name is unknown (not matching any part), fall back to all parts coordinates
+    return foundPart ? [foundPart.coordinates] : pathStepMetadata.parts.map((p) => p.coordinates);
   }
   if (pathStepMetadata.secondaryCode) {
     return pathStepMetadata.parts.map((part) => part.coordinates);
diff --git a/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/ManageTrainScheduleLeftPanel.tsx b/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/ManageTrainScheduleLeftPanel.tsx
index c827b20ebd5..37df6e00de5 100644
--- a/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/ManageTrainScheduleLeftPanel.tsx
+++ b/front/src/applications/operationalStudies/views/Scenario/components/ManageTrainSchedule/ManageTrainScheduleLeftPanel.tsx
@@ -193,6 +193,7 @@ const ManageTrainScheduleLeftPanel = ({
           itineraryModalIsOpen={itineraryModalIsOpen}
           setItineraryModalIsOpen={setItineraryModalIsOpen}
           displayTrainScheduleManagement={displayTrainScheduleManagement}
+          trainScheduleToEditData={trainScheduleToEditData}
         />
       )}
       <div
diff --git a/front/src/reducers/osrdconf/types.ts b/front/src/reducers/osrdconf/types.ts
index 08b74830117..5ad6c3449ab 100644
--- a/front/src/reducers/osrdconf/types.ts
+++ b/front/src/reducers/osrdconf/types.ts
@@ -139,7 +139,7 @@ export type PathStepV2 = {
 };
 
 export type PathStepMetadata =
-  | { isInvalid: true }
+  | { isInvalid: true; localTrackName?: string }
   | {
       type: 'trackOffset';
       isInvalid: false;
@@ -160,6 +160,11 @@ export type PathStepMetadata =
        * we won't have access to the corresponding track name in the path step location
        */
       trackName?: string;
+      /**
+       * True when the local_track_name from the location does not match any part of the matched OP.
+       * The step is still considered valid (OP was found), but the requested track is unknown.
+       */
+      isTrackNameUnknown?: boolean;
       /**
        * Data of all parts (tracks) of the path step (name + ch)
        */
diff --git a/front/src/styles/scss/applications/operationalStudies/_itineraryModal.scss b/front/src/styles/scss/applications/operationalStudies/_itineraryModal.scss
index c48eb139747..3700e2d99d1 100644
--- a/front/src/styles/scss/applications/operationalStudies/_itineraryModal.scss
+++ b/front/src/styles/scss/applications/operationalStudies/_itineraryModal.scss
@@ -293,6 +293,11 @@
             }
           }
 
+          &.is-invalid {
+            // blackAlpha10
+            background-color: rgba(0, 0, 0, 0.1);
+          }
+
           .path-step-counter:not(.is-trailing-placeholder):not(.is-only-step):hover {
             opacity: 1;
             background-color: var(--error60) !important;
@@ -407,8 +412,7 @@
               }
 
               &.invalid {
-                background-color: var(--error60);
-                border-color: var(--error30);
+                background-color: var(--info60);
               }
               &.is-only-step {
                 pointer-events: none;
@@ -423,7 +427,6 @@
 
               &.invalid {
                 border-radius: 3px;
-                box-shadow: 0 0 0 1.5px rgba(255, 104, 104, 1);
               }
             }
 
@@ -433,6 +436,11 @@
               border-radius: 4px;
             }
 
+            .track-name-unknown .ui-combo-box {
+              border-radius: 3px;
+              box-shadow: 0 0 0 1.5px var(--grey50);
+            }
+
             .map-interactions {
               margin-left: 5px;
               color: var(--primary60);
@@ -481,7 +489,7 @@
           }
 
           .invalid-step-message {
-            color: var(--error60);
+            color: var(--grey60);
             padding-left: calc(51px - var(--path-step-wrapper-padding-left));
           }
         }