diff --git a/frontend/src/views/DiaryView.vue b/frontend/src/views/DiaryView.vue
index 6e714e9..9bc3b2a 100644
--- a/frontend/src/views/DiaryView.vue
+++ b/frontend/src/views/DiaryView.vue
@@ -368,8 +368,8 @@
                             <input type="text" id="firstName" v-model="newMember.firstName" required />
                         </div>
                         <div class="form-group">
-                            <label for="lastName">Nachname:</label>
-                            <input type="text" id="lastName" v-model="newMember.lastName" required />
+                            <label for="lastName">Nachname (optional):</label>
+                            <input type="text" id="lastName" v-model="newMember.lastName" />
                         </div>
                     </div>
                     <div class="form-row">
@@ -532,7 +532,6 @@ export default {
 
         isNewMemberValid() {
             return this.newMember.firstName.trim() !== '' && 
-                   this.newMember.lastName.trim() !== '' &&
                    (this.newMember.gender === 'male' || this.newMember.gender === 'female' || this.newMember.gender === 'diverse');
         },
     },
@@ -1642,10 +1641,16 @@ export default {
         // Schnell hinzufügen Dialog Methoden
         openQuickAddDialog() {
             this.showQuickAddDialog = true;
+            
+            // Standard-Geburtsdatum: 01.01.(aktuelles Jahr - 10)
+            const currentYear = new Date().getFullYear();
+            const defaultBirthYear = currentYear - 10;
+            const defaultBirthDate = `${defaultBirthYear}-01-01`;
+            
             this.newMember = {
                 firstName: '',
                 lastName: '',
-                birthDate: '',
+                birthDate: defaultBirthDate,
                 gender: ''
             };
         },
@@ -1664,11 +1669,19 @@ export default {
             if (!this.isNewMemberValid) return;
 
             try {
+                // Standard-Geburtsdatum falls keins eingegeben wurde
+                let birthDate = this.newMember.birthDate;
+                if (!birthDate) {
+                    const currentYear = new Date().getFullYear();
+                    const defaultBirthYear = currentYear - 10;
+                    birthDate = `${defaultBirthYear}-01-01`;
+                }
+                
                 // Erstelle neues Mitglied
                 const memberData = {
                     firstName: this.newMember.firstName.trim(),
                     lastName: this.newMember.lastName.trim(),
-                    birthDate: this.newMember.birthDate || null,
+                    birthDate: birthDate,
                     gender: this.newMember.gender
                 };