Question about general property law and who actually owns land.

Alright, so here is the backstory. My family owns an 80-acre piece of land in which we used to have a cabin. About thirty years ago, my Grandma failed to keep up with the payments so my Dad stepped in and paid all of the backtaxes. In return, she decided to put his name and my Aunt's on the deed (not even sire if this is the right word). Basically she put them as the future owners. Since then, only my father has been paying taxes. My aunt has paid nothing, nor has any other family members. My grandma died about 10 years ago, and my father has still paid all the taxes. So, who technically owns the land in this case? Does my father have any better claim to the land since he has been the only one paying for it for nearly three decades? What steps need to be or could be taken to get the name in his name only? Thanks for any help.