diff --git a/frontend/src/lib/dataExport.js b/frontend/src/lib/dataExport.js
index 46e2ff1..aac6151 100644
--- a/frontend/src/lib/dataExport.js
+++ b/frontend/src/lib/dataExport.js
@@ -102,6 +102,42 @@ export function buildStatusIndex(statuses) {
   return index;
 }
 
+export function listSubjectMembers(animals, groupField) {
+  const list = [...(animals ?? [])];
+  const nameCounts = new Map();
+  for (const a of list) {
+    const n = a?.animal_name ?? '';
+    nameCounts.set(n, (nameCounts.get(n) ?? 0) + 1);
+  }
+  const members = list.map((a) => {
+    const name = a?.animal_name ?? '';
+    const label = nameCounts.get(name) > 1 ? `${name} (${a?.animal_id_string ?? ''})` : name;
+    return { id: a.id, label, animalId: a.id, group: subjectGroupValue(a, groupField) };
+  });
+  const grouped = !!groupField && groupField !== '__none__';
+  members.sort((x, y) => {
+    if (grouped) {
+      const g = String(x.group ?? '').localeCompare(String(y.group ?? ''));
+      if (g !== 0) return g;
+    }
+    return String(x.label).localeCompare(String(y.label));
+  });
+  return members;
+}
+
+export function listParameterMembers(dailyTemplate, statuses) {
+  return listExportableParams(dailyTemplate, statuses).map((p) => ({
+    id: p.id, label: p.label, param: p, group: p.group,
+  }));
+}
+
+export function listDimensionMembers(dim, { statuses, animals, dailyTemplate, groupField }) {
+  if (dim === 'date') return listDateMembers(statuses);
+  if (dim === 'subject') return listSubjectMembers(animals, groupField);
+  if (dim === 'parameter') return listParameterMembers(dailyTemplate, statuses);
+  return [];
+}
+
 // A cell has a value unless it is null, undefined, or the empty string.
 // (0 and false are real values.)
 function hasValue(v) {
diff --git a/frontend/tests/dataExport.test.js b/frontend/tests/dataExport.test.js
index fba143b..d3dd5c6 100644
--- a/frontend/tests/dataExport.test.js
+++ b/frontend/tests/dataExport.test.js
@@ -220,3 +220,49 @@ describe('buildStatusIndex', () => {
     expect(idx.get('2026-07-01').get('a2').analysis_summary.total).toBe(3);
   });
 });
+
+import { listSubjectMembers, listParameterMembers, listDimensionMembers } from '../src/lib/dataExport';
+
+describe('listSubjectMembers', () => {
+  const animals = [
+    { id: 'a2', animal_name: 'Beta', animal_id_string: 'R-002', subject_info: { grp: 'Drug' } },
+    { id: 'a1', animal_name: 'Alpha', animal_id_string: 'R-001', subject_info: { grp: 'Control' } },
+    { id: 'a3', animal_name: 'Gamma', animal_id_string: 'R-003', subject_info: { grp: 'Control' } },
+  ];
+  it('orders by name and carries group=null when no group field', () => {
+    const m = listSubjectMembers(animals, '__none__');
+    expect(m.map((s) => s.label)).toEqual(['Alpha', 'Beta', 'Gamma']);
+    expect(m.every((s) => s.group === null)).toBe(true);
+    expect(m[0]).toMatchObject({ id: 'a1', animalId: 'a1' });
+  });
+  it('clusters by group value then name when grouping is on', () => {
+    const m = listSubjectMembers(animals, 'grp');
+    expect(m.map((s) => [s.group, s.label])).toEqual([
+      ['Control', 'Alpha'], ['Control', 'Gamma'], ['Drug', 'Beta'],
+    ]);
+  });
+  it('disambiguates duplicate names with the id string', () => {
+    const dup = [
+      { id: 'a1', animal_name: 'Rat', animal_id_string: 'R-001' },
+      { id: 'a2', animal_name: 'Rat', animal_id_string: 'R-002' },
+    ];
+    expect(listSubjectMembers(dup, '__none__').map((s) => s.label)).toEqual(['Rat (R-001)', 'Rat (R-002)']);
+  });
+});
+
+describe('listParameterMembers / listDimensionMembers', () => {
+  const dailyTemplate = [{ fieldId: 'b-vitals', key: 'vitals', label: 'Vitals', builtin: true, active: true }];
+  const statuses = [{ date: '2026-07-01T00:00:00.000Z', animal_id: 'a1', analysis_summary: { total: 1 } }];
+  const animals = [{ id: 'a1', animal_name: 'Alpha', animal_id_string: 'R-001' }];
+  it('wraps params with id/label/param/group', () => {
+    const m = listParameterMembers(dailyTemplate, statuses);
+    expect(m[0]).toMatchObject({ id: '__total__', label: 'Total attempts', group: 'metrics' });
+    expect(m[0].param).toMatchObject({ kind: 'total' });
+  });
+  it('dispatches by dimension', () => {
+    const ctx = { statuses, animals, dailyTemplate, groupField: '__none__' };
+    expect(listDimensionMembers('date', ctx).map((d) => d.id)).toEqual(['2026-07-01']);
+    expect(listDimensionMembers('subject', ctx).map((d) => d.id)).toEqual(['a1']);
+    expect(listDimensionMembers('parameter', ctx)[0].id).toBe('__total__');
+  });
+});