Try not to worry to much, I suggest taking deep breaths before and after and take her to the park. I hope it works out
Hello this is a very exciting time for you all! I hope it goes well. Try to not expect too much at first, what your partner is saying is lovely but just remember it will take time to build a relationship, if youre relaxed so will the little girl. It can be tough sometimes when you get to a point where you become another parent and not dads wife. Trust and respect are the vital ingredients, it is so worth it though! You sound really enthusiastic so she's a really lucky girl to have another adult in her life that loves her.
Keep your cool and things will be fine!
I was in the same position before... Little girls warm up to adult females easier then u think. Find something she enjoys and go from there.... DONT BE A DOOR MAT!!!!!!!!! but of course dont be strict, let some things slide but be a parent figure not a friend..She isnt always going to like you, but in time she will love you and that doesnt change.. Take it one day at a time!!! and just be you.. you will be fine!!!!!!