Estate and Trust

My father just recently met a woman shortly after my mother died. (Few weeks). Moved her into the home that is in an irrevocable trust that I am trustee for. He has changed his will that upon his death , she can reside there indefinitely. The home is paid for and the belongings out part of my mothers items including jewelry that she now has possession of. If my dad questions her , she leaves him immediately, so he is somewhat stuck with her decisions which are not good for our family; just hers. Is the trust still valid if there is a will .