Can my sister's name be removed from a deed without her knowing if she left 30 years ago?

My parents house was put into their 5 children's names when my mother died. My oldest sister got into a fight with my father and left the house. When the other 4 siblings turned 18, my dad told us sign the house back to him or give him $30k. We all signed except my oldest sister who left. My father passed away and he left the house to my stepmother. Before he died he had taken another mortgage on the house to pay off his debt. My stepmother was left with a lot of bills and this payment. so from searching the internet, I have found all the deeds. I have seen she refinanced 3 times since my dad died. The new deeds have my stepmother name on it but I have not seen any with my sister's name on them.I am trying to figure out if she was removed could she fight for her 5th?