When my father remarried, I would get grounded and stuff if I didn't call my stepmother "mom". They would play psychological games with my mother and refuse to let her see me...
I moved out years ago, and I still resent them (for a lot of reasons). Thing is, I was probably a little older than your daughter at the time, and I knew inside who my real parent was.
Sorry to hear about your problem. Growing in a divorced family sucks sometimes
