S.K.
My husband has 2 daughters from a previous marriage (12,9), I have 3 sons from a previous marriage (11,9,9), and we now have a 16 month old son together. Blending our families 3 yrs ago was one of the most difficult and trying things I've ever experienced. My twins also tend to be "whiney" and his youngest daughter has a habit of talking in a baby voice ~ which drives me up the wall. The only arguements we've ever had were over disciplining (or lack thereof) the children. There were a lot of times where I felt he was being much harder on my boys than he'd ever think about being with his girls. (his girls do not live with us full-time, but he has joint custody) One thing that I promised myself is that I would not marry him (pregnant or not) until I felt like he loved my chidren and would be good to them. We've both had step-parents growing up that were less than desirable... and I promised myself that I wouldn't do that to my boys. I wanted them to grow up feeling loved and secure. I have to say, it has taken A LOT of talking, discussions ~ sometimes a bit heated, and a ton of compromise!
It's your fiance's job to talk to his daughter and demand that she respect you. If she chooses to live with her mother instead of live with you and respect you, which she very well may, then he needs to let her go. Buying her a $500 cell phone is just going to "feed the beast." She learns that she can act like a disrespectful brat and get rewarded for it,too! It's his place to discipline her and enforce the rules... it's your job to be her friend and try to "ride this out"... but you both have to be on the same page to make it work.
In the same respect... it's your job to stick up for your 9 year old when it comes to him. In the beginning, my husband (before we married) has said some not-so-nice things to my boys in the heat of the moment... and I have stuck up for them every time. It's not always easy.. but that mamabear instict comes in pretty strongly.
Would your husband be open to some family counseling? It sounds like everyone is dealing with a lot of new adjustments in their lives. A non-partial 3rd party might be able to guide you in the right direction and give you all some new ways of learning how to cope, adujust, and grow as a family. One thing is for certain, I would not marry him until these issues are resolved and you are at a peaceful place in your relationships.
Good luck to you... it's not easy, but it is POSSIBLE and can be wonderful! It takes work, but it's within reach.