diff --git a/src/applications/ivc-champva/10-10D/config/constants.js b/src/applications/ivc-champva/10-10D/config/constants.js
index 6febf1de17f4..8c1ea16dc68a 100644
--- a/src/applications/ivc-champva/10-10D/config/constants.js
+++ b/src/applications/ivc-champva/10-10D/config/constants.js
@@ -51,5 +51,22 @@ export const OPTIONAL_FILES = {
     'Proof of Legal Separation from Marriage Or Legal Union to Other',
 };
 
+// The backend needs this list so that it can properly match the attachmentId
+// on a per applicant basis to the temporary cache files that have been uploaded
+// See: https://github.com/department-of-veterans-affairs/va.gov-team/issues/96358
+export const FILE_UPLOAD_ORDER = [
+  'applicantBirthCertOrSocialSecCard',
+  'applicantAdoptionPapers',
+  'applicantStepMarriageCert',
+  'applicantSchoolCert',
+  'applicantHelplessCert',
+  'applicantRemarriageCert',
+  'applicantMedicarePartAPartBCard',
+  'applicantMedicarePartDCard',
+  'applicantMedicareIneligibleProof',
+  'applicantOhiCard',
+  'applicantOtherInsuranceCertification',
+];
+
 export const ADDITIONAL_FILES_HINT =
   'Depending on your response, you may need to submit additional documents with this application.';
diff --git a/src/applications/ivc-champva/10-10D/config/submitTransformer.js b/src/applications/ivc-champva/10-10D/config/submitTransformer.js
index c1af3461484c..795663751ec4 100644
--- a/src/applications/ivc-champva/10-10D/config/submitTransformer.js
+++ b/src/applications/ivc-champva/10-10D/config/submitTransformer.js
@@ -1,5 +1,5 @@
 import { transformForSubmit as formsSystemTransformForSubmit } from 'platform/forms-system/src/js/helpers';
-import { REQUIRED_FILES, OPTIONAL_FILES } from './constants';
+import { FILE_UPLOAD_ORDER } from './constants';
 import {
   adjustYearString,
   concatStreets,
@@ -53,13 +53,9 @@ function transformApplicants(applicants) {
       ),
       // Grab any file upload properties from this applicant and combine into a
       // supporting documents array:
-      applicantSupportingDocuments: Object.keys({
-        ...REQUIRED_FILES,
-        ...OPTIONAL_FILES,
-      })
-        .filter(k => k.includes('applicant')) // Ignore sponsor files
-        .map(f => app?.[f]) // Grab the upload obj from top-level in applicant
-        .filter(el => el), // Drop any undefineds/nulls
+      applicantSupportingDocuments: FILE_UPLOAD_ORDER.map(
+        property => app?.[property],
+      ).filter(el => el), // Drop any undefineds/nulls
     };
     transformedApp = adjustYearString(transformedApp);
     transformedApp.applicantAddress = concatStreets(
diff --git a/src/applications/ivc-champva/10-10D/tests/unit/components/File/MissingFileOverview.unit.spec.js b/src/applications/ivc-champva/10-10D/tests/unit/components/File/MissingFileOverview.unit.spec.js
index 71817250ce17..1f6a8caf8985 100644
--- a/src/applications/ivc-champva/10-10D/tests/unit/components/File/MissingFileOverview.unit.spec.js
+++ b/src/applications/ivc-champva/10-10D/tests/unit/components/File/MissingFileOverview.unit.spec.js
@@ -4,7 +4,10 @@ import { Provider } from 'react-redux';
 import { expect } from 'chai';
 import SupportingDocumentsPage from '../../../../pages/SupportingDocumentsPage';
 import { MissingFileConsentPage } from '../../../../pages/MissingFileConsentPage';
-import { REQUIRED_FILES } from '../../../../config/constants';
+import {
+  REQUIRED_FILES,
+  FILE_UPLOAD_ORDER,
+} from '../../../../config/constants';
 import {
   testComponentRender,
   getProps,
@@ -14,10 +17,52 @@ import {
   checkFlags,
 } from '../../../../../shared/components/fileUploads/MissingFileOverview';
 import MissingFileList from '../../../../../shared/components/fileUploads/MissingFileList';
+import { getAllPages } from '../../../../../shared/tests/helpers';
+import SupportingDocsVerification from '../../../../../shared/components/fileUploads/supportingDocsVerification';
 
 import formConfig from '../../../../config/form';
 import mockData from '../../../e2e/fixtures/data/test-data.json';
 
+describe('FILE_UPLOAD_ORDER constant', () => {
+  it('should match order of file upload fields present in formConfig', () => {
+    /* 
+    NOTE: FILE_UPLOAD_ORDER must be manually updated if the order
+    of file uploads in `formConfig` ever changes. This test serves to
+    make sure that happens. The backend relies on this list to properly
+    map metadata to the tmp files generated when users upload docs.
+    */
+
+    const verifier = new SupportingDocsVerification([]);
+    // We want this `FILE_UPLOAD_ORDER` to match what we pull from formConfig.
+    // This helper produces a list like:
+    //  ['applicantBirthCertOrSocialSecCard','applicantAdoptionPapers', ...]
+    const generatedArr = verifier
+      .getApplicantFileKeyNames(getAllPages(formConfig))
+      .map(el => el.name);
+
+    let orderIsSame = true;
+    generatedArr.forEach((el, idx) => {
+      if (FILE_UPLOAD_ORDER[idx] !== el) {
+        orderIsSame = false;
+      }
+    });
+
+    expect(
+      orderIsSame,
+      `Expected FILE_UPLOAD_ORDER array:
+      
+      ${FILE_UPLOAD_ORDER.join('\n\t')}
+      
+      to have same order as defined in formConfig:
+      
+      ${generatedArr.join('\n\t')}
+
+      Please verify that FILE_UPLOAD_ORDER matches the order of file upload properties defined in formConfig.
+      `,
+    ).to.be.true;
+  });
+});
+
 describe('hasReq', () => {
   const data = {
     applicants: [