Michigan probate estate dispute?

My grandmothers house and vehicle have been in probate for over a year. There has been disputes regarding the vehicle that is apart of my grandmothers estate. Before my gramma pasted my aunt was in possession of her vehicle because their car was broke down. Her and her husband used my grammas vehicle to go see her in the hospital. When my gramma pasted her car was left to no one and my aunt decided she wanted it and that she would pay a thousand dollars to each surviving benificary which she has not done.At the time the lawyer stated that the vehicle should not be titled in no ones name since it is part of the estate. My aunt then decided not to listen and took my grandmothers death certifiacate and titles it in her name..Forward a year now she is stating that she was given the vehicle and that she doesnt feel that she is entitled to pay anyone for it.The lawyers are in limbo about a decision on this because she has changed her story on this issue about three time and now is basically is making flase statements against my mother and is contradicting herself...Does anyone know if it is illegal to title a vehicle in your name with only someones death certificate? And could my mom bring charges of slander or defamation against her because she accuses my mom of false accusations that she stated in a letter written to a laywer that my mom did recieve a copy of? One more thing the laywer is now stating because of the dispute that the judge will make the final decision in this case and if my aunt is under oath and lies and her contradictions come up in the case could she be accused of perjury?