diff --git a/package.json b/package.json
index 7368a69..d4371e9 100644
--- a/package.json
+++ b/package.json
@@ -22,6 +22,7 @@
     "@quasar/quasar-ui-qcalendar": "^4.0.0-beta.10"
   },
   "devDependencies": {
+    "@flaschengeist/api": "^1.0.0-alpha.5",
     "@flaschengeist/types": "^1.0.0-alpha.8",
     "@quasar/app": "^3.2.3",
     "quasar": "^2.3.3",
diff --git a/src/components/overview/slots/TransferInviteDialog.vue b/src/components/overview/slots/TransferInviteDialog.vue
index d95ee5d..bd4cc1e 100644
--- a/src/components/overview/slots/TransferInviteDialog.vue
+++ b/src/components/overview/slots/TransferInviteDialog.vue
@@ -13,7 +13,8 @@
           filled
           :options="otherUsers"
           :option-label="(opt) => opt.display_name"
-          :multiple="isInvite"
+          :option-disable="(opt) => !isInvite && invitees.length > 0 && opt != invitees[0]"
+          multiple
           use-chips
           stack-label
           label="Dienste"
@@ -22,7 +23,7 @@
       </q-card-section>
       <!-- buttons example -->
       <q-card-actions align="right">
-        <q-btn color="primary" label="Ok" @click="invite" />
+        <q-btn color="primary" label="Ok" :disable="invitees.length === 0" @click="invite" />
         <q-btn color="primary" label="Abbrechen" @click="onDialogCancel" />
       </q-card-actions>
     </q-card>