Legal Question in Wills and Trusts in Maine

That may depend on the exact language of the will. If your father was granted a "life estate" then he can use it as if it was his own, but there are limits as to what he can do with the property, e.g., he can't sell it or allow it to fall into disrepair. If the will is vague about what was granted, your father and aunt will need to come to an agreement as to how your father can use the property. Otherwise there may need to be a legal battle over it, but I imagine that was not your grandmother's intent.