Null check for contact family names

busManager/traveller/models.py

@@ -238,8 +238,13 @@ class Family(models.Model):
             raise ValidationError(f"Phone number {failed_numbers[0]} not valid")
 
     def parent_names(self):
-        a_name = self.contact_A.first_name
-        b_name = self.contact_B.first_name
+        a_name = ""
+        b_name = ""
+        if self.contact_A:
+            a_name = self.contact_A.first_name
+        if self.contact_B:
+            b_name = self.contact_B.first_name
+
         if a_name:
             if b_name:
                 return f"{a_name} and {b_name}"