Hello and welcome to Psych Central!

Are you thinking the mom needs to get on her when she does things like talk to you disrespectfully, and when she doesn't, then she is undermining your role?

I'm wondering if mom isn't feeling some guilt over what her daughter has been through. Just a thought.....

You do have your hands full with this potential blended family, which I think is almost always the case when teenagers are involved. If the two of you are serious about your relationship, then I think it would be good if you could arrange to get together for a few couples' therapy sessions.