Will a New Deed void all other deeds including a New Will.

My spouse deceased Dec 2010 instestate. My youngest daughter added her name to a gift deed. My wife could not sign her name due to illness. I know it will take money to invalidate her deed. Because she died intestated the home should have gone to all six siblings and I as the spouse get nothing. Our wishes was to sell the home after she deceased and start a new life for myself and part funds with my kids. I paid off this home with my retirement money, how could she do this without my knowledge? I want it invalidated!
On my part can I add my children to a special warranty gift deed or quitclaim deed on a existing deed?
Also, I would like to know since I have never made a Will. Does a Will override or void any previous gift deed I created? I was told that any new Deed of any type voids the previous deed recorded. On a POA please confirm does it only allow you to manage the individual personal transcations and not award yourself with a special warranty gift deed to the deed of the individual home? What can you do to remove it invalidated? I need a Pro Bono attorney in Bexar County,Texas.