what are the legal documents i need if i wanna acknowledge my foster mother legally?

Answer 1

You don't need any legal documents to acknowledge her, just say "hello."

If you're still a minor, you can have her formally adopt you to establish a full parent-child relationship.

Answer 2

Your foster mother needs to consult a family law attorney. Every state is different and most require permission from the birth parents. All of the paperwork needs to be completed by your foster mother.