PLEASE HELP!!

My hu*****and has a daughter with his first marriage, and when he got divoiced, the daughter were verdict to his ex-wife. He showed me the court document that's why I agreed to marry him

A few months ago, my hu*****and brought his daughter to US, and let her live with us. Because I have to work, I evne sent my own 2 and half year old son to China.

Does anyone know under such situation, do I have any legal responsibilities to the 12 year old girl?

Thanks for any suggestions! PLEASE!!