>Maybe something needs adjusting there but I still thing there's a problem in having the datepicker bound to 'currentdata.birthdate' and also having the change modify it's value. Why does birthdatechange have to do that ?

It actually didn't do this originally, but I found that in this case the cleared value may not stick. Say, I removed the value and pressed save button. If I move to another guest row and return back I find that the clearing didn't work. It may have something to do with angular internals and the way the directive is written, hard to say.