HI all again. Unfortunately i have a

It depends - if the flat is her property adn she is resident at that address or not.  The antiterrorism requirement exists on paper, most people ignore it, but you could go off to the police and fill in the form, however if you are claiming residence it will be covered by your residence application.    If she is registered as the only inhabitant of her property she will have to inform the comune that her nuclear household is now 2 people and not one, (if there are reductions in imposte for single person households in your comune).