@edvin I tried to apply this on my problem but I have problems with the datatype. In my model I changed from MutableList to Observable List (var phoneNumbers by property<ObservableList<String>>()) and tried to bind the phoneNumber model. But since it is a property it only accepts contactModel.phoneNumbers.value instead of contactModelPhoneNumbers and when I run the code I get the message “Error:(133, 69) Kotlin: Type inference failed. Expected type mismatch: inferred type is MutableList<String>! but ObservableList<???> was expected” although I switched to ObservableList and initialized via contactModel.phoneNumbers.value = FXCollections.observableArrayList(“”)