Hi emjanedel
I'm not sure if I can help but I wanted to give you some support as I do know how you feel.
My DH also has a 9 year old daughter, we have been together for 6 years and we are expected our first baby in about 7 weeks :-) My DH split with his ex-partner soon after we met although they were living very separate lives. He literally moved straight in with me as he had no-where to go and took over a year to establish regular contact with his daughter. During this time he continued to pay all bills etc for his ex and in my view was more than generous. I basically had to support him which although I don't resent it meant that we never really had a courting period to our relationship as there was always arguments and stress going on and he had no support from his parents or anyone to straighten out the situation.
Finally she bought him out of the house and he began a regular every other week agreement to see his daughter. I believe this was a terrible start for us and for her as I wasn't 'allowed' to meet her for over a year and I resented that no-one stuck up for me. Basically he is a nice guy that was pushed around and blackmailed a lot - not a nice time.
Anyway things are probably as calm as they will get, we still get hassles at Christmas, birthday, any school events etc. which always leads to rows and my step daughter is going through a strange time at the moment with us having the new baby on the way and her mother just getting married again etc. its unfortunate that her parents relationship is so bad they can't talk to sort things out for her best interests.
What I wanted to say to you is if you are like me your influence and control in this situation is limited and you need to maybe take a little step back and think of yourself (this has helped me) otherwise you get too involved and only leads to you getting hurt. It is up to the parents to sort out and up to you to look after your health and sanity for you and your baby. I wouldn't worry about the neighbours, people are very small minded, I have been married to my DH for 4 years tomorrow and have never been invited to his parent's house or his brothers house, it does bother me of course but I have to try not to let it otherwise I would feel hurt all the time. Hopefully in your case time will erase the feelings they have and they will just get on with you and forget the past, if they don't its their loss.
What you say about regulating the contact with his daughter is important so I hope he can achieve that and establish a regular pattern for when your little one comes along so everyone feels safe and they know what they're doing. Even with that in place it is still a challenging time so you need to do what you can beforehand I think.
I understand what you are saying about the wedge being there, myself and my DH have this wedge too. My DH is very sensitive and tries to please everyone which normally leaves someone frustrated in the situation. I think communication is the key and honesty is very important. I try hard to support my DH but sometimes I get fed up and put my foot down but we usually resolve it in the end and as his daughter gets older it gets a bit easier. Try to keep talking it out and even enlist the help of a counsellor if necessary, but keep open to each others point of view.
It is a sensitive time but don't be terrified, the most important thing is that you love each other and keep trying together to make it work. Relationships without these challenges aren't easy so don't be hard on yourself, you can only do your best and there is so much that is beyond your control unfortunately. Try to look after yourself and support your DH but be honest with him about how you feel.
I am typing this at work so I hope I haven't come across as too opinionated, I just wanted to send you some thoughts.
Take care hon
x