I recently remarried. I have 2 teenage girls and ...

Hi,

Your new wife needs to set up some rules for her daughter, as her daughter's behavior is unacceptable. Maybe the daughter needs to be in family counseling, as she clearly shows little respect for the important people in her life. Maybe she needs to go to bootcamp. Something definitely has to be done. As for your daughters, you are their father. They need to respect you and your new wife. They need to understand that their new stepsister's behavior is unacceptable and will under no circumstances be tolerated. You can be very clear that if they choose to disrespect your new wife, there will be severe consequences (and if you know what punishments you can dole out that will make them think twice about disrespecting your new wife, you can insert them here).

its obvious to see that your wife has some favoring towards her other daughter maybe she feels bad for whatever happened to her real father and feels the need 2 let her get away with things

Well I agree with all the others, You and your wife need to set the rules and expectations straight with everyone. Disrespect towards a parent should never be tolerated, while at the same time the kids are people too and deserve fairness. I would suggest you and your wife meet with a professional together to discuss ways to improve your parenting skills in a blended famly. Then you and your wife can implement together Just how this family WILL function, they (the kids) need to know you support each other, and you both care very much for everyone to live together in a happy functioning family. It Sounds like your wifes daughter has serious issues with her behavior, and she too would benefit with some therapy if needed. Best wishes that you get through this difficult transition.