Does he have a will? I would ask a lawyer from your particular state or province what to do. Sorcha and John from Hull have very valid advice, but they may have missed some. If your sister doesn't have a lawyer, these people can give good advice for as little as $16.00/month. Prepaid legal I know I sound like an ad, but I spent an hour on the phone today with one of their lawyers, getting advice on immigration matters. I find their service to be very useful.

I hope this helps, my condolences to you and your sister.