Don’t know what to do!?

I have an eight year old from my first marriage and a three month old with my current husband. He has a four year old with his first wife who doesn’t primarily live with us. My oldest is acting out she has been stealing, talking back, and has been getting an attitude. We punish her and nothing seems to affect her. She doesn’t care if she is grounded or loses privileges and toys, writing sentences nothing works. It has been causing issues in my marriage. He says I’m to easy on her etc. her biological dad is in jail and calls her once a week after not contacting her for a year. He often tells her that my husband is not her dad which I am telling him next call that if he continues then he can no longer speak with her. Since he started calling is when she started to really act out. I don’t know what to do!?