Can we undo 10 yrs of deceit and greed by sister?

For some ten years because of deceivement and greed by sister in-law, My wifes family could not visit there dad. The eldest sister, whom hasnt worked in 12 yrs, claims disability, more lies and moved in with dad when his wife passed away, claiming she was there to take care of him. told dad lies that the rest of family was out to steal his money,unbelievable that she could be so greedy. well 1st she coerced dad to take two siblings to court, so they could not have any rights to any of dads,she also has her name on all of dads assets,bank and has been put on title of house as joint tenant, pretty much controls everything. dad had to go to emergency room because of alcohol poisioning which she waited all day and night before calling,because cousin came over and said to call. we have tried elder abuse and police, but dad is afraid to speak up on his behalf,also he his now in a convalescent hospital, while she lives in his house for free, sorry her house so she says when dad asked to go home.. I guess are only choice is to take her to court. the rest of us work for a living and it wont be easy for getting money for a lawyer, any other suggestions. remember she has joint accts on everything and possibly p.o.a. I will appreciate any suggestions