diff --git a/src/app/features/registries/components/custom-step/custom-step.component.html b/src/app/features/registries/components/custom-step/custom-step.component.html
index 022d7d005..e561d3af7 100644
--- a/src/app/features/registries/components/custom-step/custom-step.component.html
+++ b/src/app/features/registries/components/custom-step/custom-step.component.html
@@ -163,7 +163,7 @@ <h3 class="mb-2">{{ 'files.actions.uploadFile' | translate }}</h3>
                   [filesViewOnly]="filesViewOnly()"
                   (attachFile)="onAttachFile($event, q.responseKey!)"
                   (openFile)="onOpenFile($event)"
-                  (removeFromAttachedFiles)="removeFromAttachedFiles($event, q.responseKey!)"
+                  (removeFromAttachedFiles)="removeDeletedFileFromAllQuestions($event)"
                 ></osf-files-control>
               </div>
             }
diff --git a/src/app/features/registries/components/custom-step/custom-step.component.spec.ts b/src/app/features/registries/components/custom-step/custom-step.component.spec.ts
index b1c3b39f9..97f2e05c1 100644
--- a/src/app/features/registries/components/custom-step/custom-step.component.spec.ts
+++ b/src/app/features/registries/components/custom-step/custom-step.component.spec.ts
@@ -6,6 +6,7 @@ import { Mock } from 'vitest';
 
 import { TestBed } from '@angular/core/testing';
 import { FormGroup } from '@angular/forms';
+import { By } from '@angular/platform-browser';
 import { ActivatedRoute, Router, UrlTree } from '@angular/router';
 
 import { UserSelectors } from '@osf/core/store/user/user.selectors';
@@ -298,7 +299,7 @@ describe('CustomStepComponent', () => {
       pages: [createPage([createQuestion({ responseKey: 'files', fieldType: FieldType.File })])],
       stepsData: { files: [] },
     });
-    component.attachedFiles['files'] = [{ file_id: 'file-1', name: 'existing.txt' }];
+    component.attachedFiles['files'] = [{ ...filePayload, file_id: 'file-1', name: 'existing.txt' }];
     const emitSpy = vi.spyOn(component.updateAction, 'emit');
 
     component.onAttachFile(FileModelMock.simple({ id: 'file-1' }), 'files');
@@ -307,12 +308,28 @@ describe('CustomStepComponent', () => {
     expect(emitSpy).not.toHaveBeenCalled();
   });
 
+  it('should not attach the same file twice before the draft is saved', () => {
+    const { component } = setup({
+      pages: [createPage([createQuestion({ responseKey: 'files', fieldType: FieldType.File })])],
+      stepsData: { files: [] },
+    });
+    const mockFile = FileModelMock.simple({ id: 'new-file', name: 'new.txt' });
+
+    component.onAttachFile(mockFile, 'files');
+    component.onAttachFile(mockFile, 'files');
+
+    expect(component.attachedFiles['files']).toEqual([
+      expect.objectContaining({ file_id: 'new-file', file_name: 'new.txt', name: 'new.txt' }),
+    ]);
+  });
+
   it('should warn when the attachment limit is reached', () => {
     const { component, toastMock } = setup({
       pages: [createPage([createQuestion({ responseKey: 'files', fieldType: FieldType.File })])],
       stepsData: { files: [] },
     });
     component.attachedFiles['files'] = Array.from({ length: FILE_COUNT_ATTACHMENTS_LIMIT }, (_, i) => ({
+      ...filePayload,
       file_id: `f-${i}`,
       name: `f-${i}`,
     }));
@@ -364,6 +381,65 @@ describe('CustomStepComponent', () => {
     expect(emitSpy).not.toHaveBeenCalled();
   });
 
+  it('should remove a deleted file from file questions on every page', () => {
+    const otherFile: FilePayloadJsonApi = { ...filePayload, file_id: 'f2', file_name: 'other.pdf' };
+    const { component } = setup({
+      pages: [
+        createPage([createQuestion({ responseKey: 'files', fieldType: FieldType.File })]),
+        createPage([createQuestion({ responseKey: 'otherFiles', fieldType: FieldType.File })]),
+      ],
+      stepsData: { files: [filePayload, otherFile], otherFiles: [filePayload] },
+    });
+    const emitSpy = vi.spyOn(component.updateAction, 'emit');
+
+    component.removeDeletedFileFromAllQuestions('f1');
+
+    expect(component.attachedFiles['files']).toEqual([{ ...otherFile, name: 'other.pdf' }]);
+    expect(component.stepForm.get('files')?.value).toEqual([{ ...otherFile, name: 'other.pdf' }]);
+    expect(emitSpy).toHaveBeenCalledWith({ files: [otherFile], otherFiles: [] });
+  });
+
+  it('should remove a file attached on this page when it is deleted', () => {
+    const { component } = setup({
+      pages: [createPage([createQuestion({ responseKey: 'files', fieldType: FieldType.File })])],
+      stepsData: { files: [] },
+    });
+    component.onAttachFile(FileModelMock.simple({ id: 'new-file' }), 'files');
+    const emitSpy = vi.spyOn(component.updateAction, 'emit');
+
+    component.removeDeletedFileFromAllQuestions('new-file');
+
+    expect(component.attachedFiles['files']).toEqual([]);
+    expect(emitSpy).toHaveBeenCalledWith({ files: [] });
+  });
+
+  it('should not emit when the deleted file is not attached', () => {
+    const { component } = setup({
+      pages: [createPage([createQuestion({ responseKey: 'files', fieldType: FieldType.File })])],
+      stepsData: { files: [filePayload] },
+    });
+    const emitSpy = vi.spyOn(component.updateAction, 'emit');
+
+    component.removeDeletedFileFromAllQuestions('unknown');
+
+    expect(component.attachedFiles['files']).toHaveLength(1);
+    expect(emitSpy).not.toHaveBeenCalled();
+  });
+
+  it('should handle a file deleted from the files list', () => {
+    const { component, fixture } = setup({
+      pages: [createPage([createQuestion({ responseKey: 'files', fieldType: FieldType.File })])],
+      stepsData: { files: [filePayload] },
+    });
+    const deleteSpy = vi.spyOn(component, 'removeDeletedFileFromAllQuestions');
+
+    fixture.debugElement
+      .query(By.directive(FilesControlComponent))
+      .triggerEventHandler('removeFromAttachedFiles', 'f1');
+
+    expect(deleteSpy).toHaveBeenCalledWith('f1');
+  });
+
   it('should open file preview when draftId and guid exist', () => {
     const urlTree = {} as UrlTree;
     const { component, mockRouter } = setup({
diff --git a/src/app/features/registries/components/custom-step/custom-step.component.ts b/src/app/features/registries/components/custom-step/custom-step.component.ts
index bc4a933df..6b6245a00 100644
--- a/src/app/features/registries/components/custom-step/custom-step.component.ts
+++ b/src/app/features/registries/components/custom-step/custom-step.component.ts
@@ -38,7 +38,7 @@ import { CustomValidators } from '@osf/shared/helpers/custom-form-validators.hel
 import { findChangedFields } from '@osf/shared/helpers/find-changed-fields';
 import { FileModel } from '@osf/shared/models/files/file.model';
 import { FilePayloadJsonApi } from '@osf/shared/models/files/file-payload-json-api.model';
-import { PageSchema } from '@osf/shared/models/registration/page-schema.model';
+import { PageSchema, Question } from '@osf/shared/models/registration/page-schema.model';
 import { ToastService } from '@osf/shared/services/toast.service';
 
 import { FilesMapper } from '../../mappers/files.mapper';
@@ -105,6 +105,12 @@ export class CustomStepComponent implements OnDestroy {
     }
     return 'shared.files.description';
   });
+  private readonly fileQuestionKeys = computed(() =>
+    this.pages()
+      .flatMap((page) => this.getPageQuestions(page))
+      .filter((q) => q.fieldType === FieldType.File)
+      .map((q) => q.responseKey as string)
+  );
 
   stepForm: FormGroup = this.fb.group({});
   attachedFiles: Record<string, AttachedFile[]> = {};
@@ -130,11 +136,34 @@ export class CustomStepComponent implements OnDestroy {
       return;
     }
 
-    this.attachedFiles[questionKey] = [...this.attachedFiles[questionKey], file];
+    const attachedFile = { ...FilesMapper.toFilePayload(file), name: file.name };
+    this.attachedFiles[questionKey] = [...this.attachedFiles[questionKey], attachedFile];
     this.stepForm.patchValue({ [questionKey]: this.attachedFiles[questionKey] });
     this.updateAction.emit(this.getFormPayload());
   }
 
+  removeDeletedFileFromAllQuestions(fileId: string): void {
+    const payload: Record<string, FilePayloadJsonApi[]> = {};
+
+    for (const key of this.fileQuestionKeys()) {
+      const files = this.attachedFiles[key] ?? this.getSavedFiles(key);
+      if (!files.some((f) => f.file_id === fileId)) {
+        continue;
+      }
+
+      const remaining = files.filter((f) => f.file_id !== fileId);
+      if (this.attachedFiles[key]) {
+        this.attachedFiles[key] = remaining;
+        this.stepForm.patchValue({ [key]: remaining });
+      }
+      payload[key] = this.mapFilesToPayload(remaining);
+    }
+
+    if (Object.keys(payload).length) {
+      this.updateAction.emit(payload);
+    }
+  }
+
   onOpenFile(file: FileModel): void {
     if (this.draftId() && file.guid) {
       const url = this.router.serializeUrl(this.router.createUrlTree([this.draftId(), 'files', file.guid, 'preview']));
@@ -192,19 +221,13 @@ export class CustomStepComponent implements OnDestroy {
   private initStepForm(page: PageSchema): void {
     this.stepForm = this.fb.group({});
     this.attachedFiles = {};
-    const questions = [
-      ...(page.questions || []),
-      ...(page.sections?.flatMap((section) => section.questions ?? []) ?? []),
-    ];
-
-    questions.forEach((q) => {
+    this.getPageQuestions(page).forEach((q) => {
       const controlName = q.responseKey as string;
       const control = this.createControl(q.fieldType!, controlName, q.required);
       if (!control) return;
 
       if (q.fieldType === FieldType.File) {
-        const files = (this.stepsData()[controlName] as FilePayloadJsonApi[] | undefined) || [];
-        this.attachedFiles[controlName] = files.map((file) => ({ ...file, name: file.file_name }));
+        this.attachedFiles[controlName] = this.getSavedFiles(controlName);
       }
 
       this.stepForm.addControl(controlName, control);
@@ -270,13 +293,16 @@ export class CustomStepComponent implements OnDestroy {
     return values;
   }
 
+  private getPageQuestions(page: PageSchema): Question[] {
+    return [...(page.questions || []), ...(page.sections?.flatMap((section) => section.questions ?? []) ?? [])];
+  }
+
+  private getSavedFiles(questionKey: string): AttachedFile[] {
+    const files = (this.stepsData()[questionKey] as FilePayloadJsonApi[] | undefined) || [];
+    return files.map((file) => ({ ...file, name: file.file_name }));
+  }
+
   private mapFilesToPayload(files: AttachedFile[]): FilePayloadJsonApi[] {
-    return files.map((f) => {
-      if (f.file_id) {
-        const { name: _, ...payload } = f;
-        return payload as FilePayloadJsonApi;
-      }
-      return FilesMapper.toFilePayload(f as FileModel);
-    });
+    return files.map(({ name: _, ...payload }) => payload);
   }
 }
diff --git a/src/app/features/registries/models/attached-file.model.ts b/src/app/features/registries/models/attached-file.model.ts
index 458dac9cf..acc6d3b39 100644
--- a/src/app/features/registries/models/attached-file.model.ts
+++ b/src/app/features/registries/models/attached-file.model.ts
@@ -1,3 +1,3 @@
-import { FileModel } from '@osf/shared/models/files/file.model';
+import { FilePayloadJsonApi } from '@osf/shared/models/files/file-payload-json-api.model';
 
-export type AttachedFile = Partial<FileModel & { file_id: string }>;
+export type AttachedFile = FilePayloadJsonApi & { name: string };