Does a will need to go to probate if the is nothing in the estate? The property was transferred by- power of attorney prior to death.

Do you need to probate if there was nothing in the estate: no - probate is the process by which you register the will and obtain a certificate indicating you have the authority to act on behalf of the estate for purposes of selling or disposing of estate assets.  If there is nothing in the estate, there is no reason to probate. As to the second set of questions - any one can sue - if they have the money to file a complaint they can sue, there is no prohibition.  however, if there is nothing in the estate, there is no relief that can be obtained.  The person suing the estate would have to claim that the assets were transferred improperly or that the person lacked capacity, or that the sibling caretaker abused their position.  this would require proof of undue influence, and other factors and is often very difficult to prove, especially if the transfers occurred several years before death.