Does my fiancé's aunt have any claim and does he need to file a succession if his name is on everything but the land?

My fiancé's father recently passed away and a few months ago, his grandmother (she is still alive) signed over everything to his dad. This includes give or take 20 acres of lot, lots of tools and the house that she is still living in etc. According to the paperwork, she is allowed to stay there as long as she lives/wants which we have absolutely no problem with. We love her dearly. Our problem is my fiancé's grandmother has a few other children, one of which lives next door and is going to have a major problem with this she is all about money. Is there any way that she can possibly cause legal issues? Also back in May or June of this year he put my fiancé's name on everything except the land. He signed a full power of attorney. Do we still need to file a succession if my fiancé has a sister, but everything was left to my fiancé in the will? There will be no contesting the will because he's doing his sister right.