Finally a Mama I can relate to! I am the step-mom to an amazing 10 year old girl. My husband and I began dating when she was 3 and I moved in when she was 4. I did not have children at the time (I now have a 3 yr old and a 7 month old). First off I have to say you are amazing for being such a big person about this (as I have told my husbands ex on many occasions). You are putting your daughter first as it should be but unfourtunately that is few and far between. Being the step-mom let me tell you that this girl will be very intimidated by you, so it may be nice of you (if you feel like it) to extend your appreciation of her talking to you. I would just make sure that you guys are on the same page as far as your daughters schedule, eating habits, whats expected of her, etc. Give her some hypothetical situations and ask her how she would handle them (your daughter hit/or got hit at the playground, she woke up in the middle of the night very sick, she got into something she wasn't supposed to). Also make sure you are all on the same page (your husband and daughter included) about who does the punishing. I do not/nor have I ever punished my step daughter. I set this rule because I feel like that is a line a I am not willing to cross. As she got older we set up and kind of action/consequence plan, so I didn't punish but just reminded her of the consequence (which I never have to do because she's such a great kid) If there ever is something that I feel like needs to be addressed she understands that I will talk to Daddy about it and he will discuss with her what he needs to. Also, let her know that she can call you with questions ( I would much rather ask her Mom how she wanted me to handle something, than make a decision and that not be how her Mom would have done it.) I have alot of respect for being a mother and have never tried to be a replacement just an additional heart full of love!, hopefully your husband's girlfriend will have the same view. Good luck!