ths is a tricky one as it is a mod to car but...as you are claiming on her insurance it shouldn't matter as if it was your own i imagine you would have had to declare it. Also it is a security feature so i guess it is not like some silly whale-tail spoiler you have bolted on. I would go and get some quotes from places you know about in your area inclding the keypad fitting and send them to her insurance. I have seen people over here take cars to tuning places and geting bodykits fitted on the insurance and either paying the extra or getting it covered fully by the insurance as the tuning place and the bodykit was cheaper than the original bumpers fitted at an approved bodyshop or at a main dealer. The insurance quote will normally be top dollar from a dealer crash repair centre so shop around and see if you can get a similar quote including you mod and negotiate with her insurance.