For one and like other have said below, why is your name 2boysand1girl? If you do not include her in your name, then as a child of divorce and step parents she can sense that you don't feel the same about her as you do the other kids. Just like I can read between the lines so can she, she can see the unspoken words as well.
She's 10 and you are saying she doesn't care? You say that you pay a lot of money because he has a good job. I can tell you money is not the issue, it should be none of her business about the money. However, it does seem that everyone (including you, mom, grandma, possbily dad) make it about the money. She has no idea what it means to "give up" family, church, friends, as she shouldn't have to know at 10.
Jo W. is right you ALL need counseling. Whether or not any adult in the situation likes it you are apart of her life, and if you are not including this child in everything then she's not going to want to come around.
I wacthed my mom as a stepmom, she was HORRIBLE, but sure as if my step mom was to act that way towards me she would have been all bent out of shape. Luckily my step mom was a much better one than my mom. But my step brother hardly ever came around because of the way my mom and his mom acted! Get the mom to talk to you...don't make it about you and her make it about your DAUGHTER!