My step daughter (7) constantly snubs me and I need some help!

Context: my partner and I have been together 2 years now and he has a lovely 7 year old daughter. I’ve known her for about a year and he parents have been separated for just over 2 years. Her dad and I met just after he left the family home. She knows I had nothing to do with her parents splitting up.She’s a lovely little girl and is bright and funny and sweet but also sassy and cheeky and can have a bit of an attitude. I classify all of this as normal for a 7 y.o though.My partner and I have lived together for just over a year now and she is with us one night every week and every other weekend. At first this was very tricky as she would reject me a lot and I was not involved in almost any part of her visits to our house. I tried not to take this personally as she’s a kid and I’m a stranger but it did hurt me a bit. Things have gotten better and I’m allowed to help her with getting a snack or tying up her hair now.However she makes a point of choosing to snub me in favour of her dad bear constantly. If I sit down and her dad sits next to me she will ask me to move so she can’t sit next to him, if I chose her something to wear she will ask her dad to chose her something else, if we’re sitting on the sofa she will make sure she sits away from me and close to her dad, and this constant snubbing is starting to affect me.I’m mostly worried that she feels she had to show him that she chooses him over me. It shouldn’t be like this.Her and I get along well, when she lets me in we play games and laugh and chat and do activities together. She has told her dad and mum that she likes me. I try extra hard to make things nice and special for her visits to our house so she feels loved and wanted and included. But I feel like the odd one out when she’s with us as they feel like family and I feel decidedly left out.I thought that when she accepted that her mum and dad aren’t getting back together (they both have new partners) that her obstacles towards me would come down and we would be able to build a relationship but I feel totally stuck and like she is making it hard for me to love her the way I feel a mum like figure should.I want to ask my partner to have a chat with her but not sure what to say and how to get this across to her so we can all move forward. Any advice?TL:DR: I feel left out of my family because of my step daughter and need help with how to talk to her. via /r/Parenting https://ift.tt/2SWWtFg