We have the same issue at our house. I understand how hard it is when youhave been there for some time and things aren't progressing so well. My daughter is 9 and the only girl amoungst some rather rough and tumble boys. My partner and my daughter do not get on and nomatter how hard he tries, things seem to get better in waves and then worse again. It frustrating for me being both the partner and the mother and not wanting either hurt. Sometimes my partner brings it on himself by over-doing the games they play, when he knows she hates it. He has yet to find a middle ground so they can play toether and has somewhat of a "my way or the highway" attitude when it comes to the games they play. A lot of the time though, my daughter just wont budge an inch and is hell bent on holding a grudge for all the times he roughed her up to much or played boy games with her. SHe hates that she is no longer the sole centre of my attention and I dont baby her anymore..I made the decision that it was time for her to be a little more independent around the same time I go together with my partner. She blames him for that and its been chaos ever since. Find that middle ground if you can and find a way for your partner to discretely plant the idea in her head that its the best thing she can do for herself, you and the family. My daughter responds more when I find ways for her to think its her idea to make peace and she is doing it for her reasons. I hope that made some sense

Something simple to do is to just find common grounds. Find something you both relate to. I've found that It's one of the best approaches to minimize defensiveness.

Have the same problem with my eldest, she is always trying stir things up with my partner and untill of late I was sticking up for her as I felt I had to protect her from being upset. The eldest is always the hardest to convince that you are their to care for because they feel that because they are the eldest so therefore have to protect their mum. I have watched my partner and daughters relationship change through doing this.

Make a little extra effort with her. Ask her how her day was at school, Christmas is coming up so maybe you and her can pick out mums present or make a card together. Find some common interests like fishing, sport or other hobbies and do it together. Things will get better it is just getting her to trust you.

One major piece of advice for any parent is that you ARE their parent NOT their friend. You cant just be a parent you have TO parent. This means that this young lady deserves you to be strong, available and most of all consistant. Alot of children in  home with one parent and one step parent will veiw the 'intruder" with suspicion. They only trust the parent who has been with them consistantly. She has obviously not developed the trust to enable her to get close and feel safe.

The only thing you can do is be there, remain predicable and become a constant in her life. You dont need to be a friend she will make plenty of those, you need to be a parent figure and that can take time and trust as it is the most important role you will ever do.

I admire your concern and your caring....enough to ask advice to do it right. Pat yourself on the back as you are obviously very special.

Best wishes, Miriam