diff --git a/frontend/src/pages/user-file.vue b/frontend/src/pages/user-file.vue
index 7b95c55..abeb856 100644
--- a/frontend/src/pages/user-file.vue
+++ b/frontend/src/pages/user-file.vue
@@ -1,5 +1,5 @@
 <script lang="ts" setup>
-  import { onMounted, ref } from 'vue'
+  import { onMounted, reactive, ref } from 'vue'
   import { useRoute, useRouter } from 'vue-router'
   import { auth } from '@/auth'
 
@@ -11,6 +11,7 @@
   }
   interface LinkedEntity {
     entity: { id: number, name: string, identifier: string, fields: Field[] }
+    relationshipField: Field
     records: Record<string, unknown>[]
   }
   interface UserFile {
@@ -23,6 +24,66 @@
   const file = ref<UserFile>()
   const loading = ref(true)
   const errorMessage = ref('')
+  const saving = ref(false)
+  const addingChildKey = ref('')
+  const childValues = reactive<Record<string, Record<string, string | boolean>>>({})
+
+  function childKey (linked: LinkedEntity) {
+    return `${linked.entity.id}-${linked.relationshipField.id}`
+  }
+
+  function editableFields (linked: LinkedEntity) {
+    return linked.entity.fields.filter(field => field.id !== linked.relationshipField.id)
+  }
+
+  function inputType (field: Field) {
+    if (['NUMBER', 'RELATIONSHIP', 'USER'].includes(field.type)) return 'number'
+    if (field.type === 'DATE') return 'date'
+    if (field.type === 'EMAIL') return 'email'
+    if (field.type === 'PHONE') return 'tel'
+    return 'text'
+  }
+
+  function startAddingChild (linked: LinkedEntity) {
+    const key = childKey(linked)
+    childValues[key] = {}
+    for (const field of editableFields(linked)) {
+      childValues[key][field.identifier] = field.type === 'BOOLEAN' ? false : ''
+    }
+    addingChildKey.value = key
+    errorMessage.value = ''
+  }
+
+  async function addChild (linked: LinkedEntity) {
+    const key = childKey(linked)
+    const body = new URLSearchParams()
+    for (const field of editableFields(linked)) {
+      body.set(field.identifier, String(childValues[key][field.identifier] ?? ''))
+    }
+    saving.value = true
+    errorMessage.value = ''
+    try {
+      const response = await fetch(
+        `/api/users/${route.params.userId}/children/${encodeURIComponent(linked.entity.name)}/${linked.relationshipField.id}`,
+        {
+          method: 'POST',
+          headers: {
+            'Authorization': `Bearer ${auth.token}`,
+            'Content-Type': 'application/x-www-form-urlencoded',
+          },
+          body,
+        },
+      )
+      if (!response.ok) throw new Error('Child create failed')
+      const created = await response.json() as { values: Record<string, unknown> }
+      linked.records.push(created.values)
+      addingChildKey.value = ''
+    } catch {
+      errorMessage.value = `The ${linked.entity.name} could not be added. Check the field values and try again.`
+    } finally {
+      saving.value = false
+    }
+  }
 
   function displayValue (value: unknown) {
     if ([null, undefined, ''].includes(value as null | undefined | string)) return '—'
@@ -71,14 +132,36 @@
         No entities with user references are configured.
       </p>
 
-      <article v-for="linked in file.linkedEntities" :key="linked.entity.id" class="entity-card">
+      <article v-for="linked in file.linkedEntities" :key="childKey(linked)" class="entity-card">
         <div class="entity-heading">
           <div>
             <h2>{{ linked.entity.name }}</h2>
             <p>{{ linked.records.length }} linked {{ linked.records.length === 1 ? 'record' : 'records' }}</p>
           </div>
+
+          <button type="button" @click="startAddingChild(linked)">Add {{ linked.entity.name }}</button>
         </div>
 
+        <form
+          v-if="addingChildKey === childKey(linked)"
+          :aria-label="`Add ${linked.entity.name}`"
+          class="child-form"
+          @submit.prevent="addChild(linked)"
+        >
+          <label v-for="field in editableFields(linked)" :key="field.id">
+            <span>{{ field.name }}</span>
+
+            <input v-if="field.type === 'BOOLEAN'" v-model="childValues[childKey(linked)][field.identifier]" type="checkbox">
+
+            <input v-else v-model="childValues[childKey(linked)][field.identifier]" :type="inputType(field)">
+          </label>
+
+          <div class="form-actions">
+            <button :disabled="saving" type="submit">{{ saving ? 'Adding…' : `Add ${linked.entity.name}` }}</button>
+            <button :disabled="saving" type="button" @click="addingChildKey = ''">Cancel</button>
+          </div>
+        </form>
+
         <p v-if="linked.records.length === 0" class="no-records">No records linked to this user.</p>
 
         <div v-else class="table-scroll">
@@ -130,7 +213,7 @@
   header > p:last-child, .entity-heading p { color: var(--v0-on-surface-variant); }
   .role-badge { padding: 0.25rem 0.6rem; border-radius: 999px; color: var(--v0-primary); background: color-mix(in srgb, var(--v0-primary) 14%, transparent); font-size: 0.8rem; font-weight: 700; }
   .entity-card, .empty-state { margin-bottom: 1.25rem; overflow: hidden; border: 1px solid var(--v0-divider); border-radius: 1rem; background: var(--v0-surface); }
-  .entity-heading { padding: 1.25rem; border-bottom: 1px solid var(--v0-divider); }
+  .entity-heading { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: 1.25rem; border-bottom: 1px solid var(--v0-divider); }
   .entity-heading p { margin: 0.35rem 0 0; font-size: 0.9rem; }
   .empty-state, .no-records { padding: 1.5rem; }
   .table-scroll { overflow-x: auto; }
@@ -138,5 +221,14 @@
   th, td { padding: 0.85rem 1rem; border-bottom: 1px solid var(--v0-divider); }
   th { color: var(--v0-on-surface-variant); font-size: 0.75rem; text-transform: uppercase; }
   tbody tr:last-child td { border-bottom: 0; }
+  button { padding: 0.65rem 0.9rem; border: 1px solid var(--v0-divider); border-radius: 0.6rem; color: inherit; background: var(--v0-surface); font: inherit; font-weight: 700; cursor: pointer; }
+  button[type="submit"] { color: var(--v0-on-primary); border-color: var(--v0-primary); background: var(--v0-primary); }
+  button:disabled { opacity: 0.55; cursor: wait; }
+  .child-form { display: grid; grid-template-columns: repeat(auto-fit, minmax(12rem, 1fr)); gap: 1rem; padding: 1.25rem; border-bottom: 1px solid var(--v0-divider); }
+  .child-form label { display: grid; gap: 0.45rem; }
+  .child-form label > span { color: var(--v0-on-surface-variant); font-size: 0.8rem; font-weight: 700; text-transform: uppercase; }
+  input { width: 100%; padding: 0.65rem 0.75rem; border: 1px solid var(--v0-divider); border-radius: 0.5rem; color: inherit; background: var(--v0-background); font: inherit; }
+  input[type="checkbox"] { width: 1.1rem; }
+  .form-actions { display: flex; align-items: end; justify-content: flex-end; gap: 0.5rem; }
   .sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0, 0, 0, 0); }
 </style>
diff --git a/frontend/tests/user-file.spec.ts b/frontend/tests/user-file.spec.ts
index 23969c9..e95e9df 100644
--- a/frontend/tests/user-file.spec.ts
+++ b/frontend/tests/user-file.spec.ts
@@ -12,6 +12,7 @@ async function useAdminSession (page: Page) {
 
 test('admin opens a user file and views a linked entity record', async ({ page }) => {
   let projectTitle = 'Website refresh'
+  const projects: Record<string, unknown>[] = [{ id: 42, title: 'Website refresh', owner: 7 }]
   const tasks: Record<string, unknown>[] = []
   const projectResponse = () => ({
     entity: {
@@ -68,10 +69,20 @@ test('admin opens a user file and views a linked entity record', async ({ page }
             { id: 12, name: 'Owner', identifier: 'owner', type: 'USER' },
           ],
         },
-        records: [{ id: 42, title: 'Website refresh', owner: 7 }],
+        relationshipField: { id: 12, name: 'Owner', identifier: 'owner', type: 'USER' },
+        records: projects,
       }],
     },
   }))
+  await page.route('**/api/users/7/children/Project/12', async route => {
+    const values = new URLSearchParams(route.request().postData() ?? '')
+    const created = { id: 43, title: values.get('title'), owner: 7 }
+    projects.push(created)
+    await route.fulfill({
+      status: 201,
+      json: { entity: projectResponse().entity, values: created, children: [] },
+    })
+  })
   await page.route('**/api/users/7/entities/Project/records/42', async route => {
     if (route.request().method() === 'PATCH') {
       const values = new URLSearchParams(route.request().postData() ?? '')
@@ -100,6 +111,12 @@ test('admin opens a user file and views a linked entity record', async ({ page }
   await expect(page.getByRole('heading', { name: 'Project' })).toBeVisible()
   await expect(page.getByRole('row').filter({ hasText: 'Website refresh' })).toContainText('7')
 
+  await page.getByRole('button', { name: 'Add Project' }).click()
+  const projectForm = page.getByRole('form', { name: 'Add Project' })
+  await projectForm.getByLabel('Title').fill('Mobile application')
+  await projectForm.getByRole('button', { name: 'Add Project' }).click()
+  await expect(page.getByRole('row').filter({ hasText: 'Mobile application' })).toContainText('7')
+
   await page.getByRole('link', { name: 'View Project record 42' }).click()
   await expect(page).toHaveURL('/users/7/entities/Project/records/42')
   await expect(page.getByRole('heading', { name: 'Project #42' })).toBeVisible()
diff --git a/src/main/kotlin/dev/mduchene/bolts/entity/EntityRecordRepository.kt b/src/main/kotlin/dev/mduchene/bolts/entity/EntityRecordRepository.kt
index c5e6b44..e44b290 100644
--- a/src/main/kotlin/dev/mduchene/bolts/entity/EntityRecordRepository.kt
+++ b/src/main/kotlin/dev/mduchene/bolts/entity/EntityRecordRepository.kt
@@ -8,6 +8,7 @@ import java.time.temporal.TemporalAccessor
 
 data class LinkedEntityRecords(
     val entity: EntityDefinition,
+    val relationshipField: EntityField,
     val records: List<Map<String, Any?>>,
 )
 
@@ -37,20 +38,42 @@ class EntityRecordRepository(
                 .filter { entity ->
                     entity.identifier.lowercase() in tables && entity.fields.any { it.type == FieldType.USER }
                 }
-                .map { entity ->
-                    val userFields = entity.fields.filter { it.type == FieldType.USER }
+                .flatMap { entity ->
+                    entity.fields.filter { it.type == FieldType.USER }.map { userField ->
                     val columns = listOf("id") + entity.fields.map(EntityField::identifier)
-                    val predicate = userFields.joinToString(" OR ") { "${quote(it.identifier)} = ?" }
                     val sql = "SELECT ${columns.joinToString { quote(it) }} FROM ${quote(entity.identifier)} " +
-                        "WHERE $predicate ORDER BY \"id\""
+                        "WHERE ${quote(userField.identifier)} = ? ORDER BY \"id\""
                     val records = connection.prepareStatement(sql).use { statement ->
-                        userFields.indices.forEach { statement.setLong(it + 1, userId) }
+                        statement.setLong(1, userId)
                         statement.executeQuery().use { result -> result.toRecords(columns) }
                     }
-                    LinkedEntityRecords(entity, records)
+                    LinkedEntityRecords(entity, userField, records)
+                    }
                 }
         }
 
+    fun createChildForUser(
+        userId: Long,
+        childEntityName: String,
+        userFieldId: Long,
+        submittedValues: Map<String, String>,
+    ): EntityRecord? {
+        val child = entities.findAll().firstOrNull { it.name == childEntityName } ?: return null
+        val userField = child.fields.firstOrNull {
+            it.id == userFieldId && it.type == FieldType.USER
+        } ?: return null
+        val fields = child.fields
+        val sql = "INSERT INTO ${quote(child.identifier)} (${fields.joinToString { quote(it.identifier) }}) " +
+            "VALUES (${fields.joinToString { "?" }}) RETURNING \"id\""
+        val childId = checkNotNull(database.queryOne(sql, bind = {
+            fields.forEachIndexed { index, field ->
+                if (field.id == userField.id) setLong(index + 1, userId)
+                else bindField(index + 1, field, submittedValues[field.identifier].orEmpty())
+            }
+        }) { getLong("id") })
+        return findChildRecord(child, childId)
+    }
+
     fun findRecordLinkedToUser(userId: Long, entityName: String, recordId: Long): EntityRecord? {
         val definitions = entities.findAll()
         val entity = definitions.firstOrNull { it.name == entityName } ?: return null
diff --git a/src/main/kotlin/dev/mduchene/bolts/web/UserController.kt b/src/main/kotlin/dev/mduchene/bolts/web/UserController.kt
index 6f8ce93..190700d 100644
--- a/src/main/kotlin/dev/mduchene/bolts/web/UserController.kt
+++ b/src/main/kotlin/dev/mduchene/bolts/web/UserController.kt
@@ -38,6 +38,29 @@ class UserController(
                 ),
             )
         }
+        routes.post("/api/users/{userId}/children/{childEntityName}/{fieldId}") { ctx ->
+            if (!ctx.requireAdmin(loginService)) return@post
+            val userId = ctx.pathParam("userId").toLongOrNull()
+            val childEntityName = ctx.pathParam("childEntityName")
+            val fieldId = ctx.pathParam("fieldId").toLongOrNull()
+            if (userId == null || fieldId == null || users.findById(userId) == null) {
+                ctx.notFound()
+                return@post
+            }
+            try {
+                val child = records.createChildForUser(
+                    userId,
+                    childEntityName,
+                    fieldId,
+                    ctx.singleFormParams(),
+                )
+                if (child == null) ctx.notFound() else ctx.status(201).json(child)
+            } catch (exception: IllegalArgumentException) {
+                ctx.badRequest(exception.message ?: "Invalid field value")
+            } catch (_: SQLException) {
+                ctx.badRequest("The child record violates an entity constraint")
+            }
+        }
         routes.get("/api/users/{userId}/entities/{entityName}/records/{recordId}") { ctx ->
             if (!ctx.requireAdmin(loginService)) return@get
             val userId = ctx.pathParam("userId").toLongOrNull()