I am not nor have I ever been part of a blended family but the situation you have described just seems really bad to me.

I believe in a "my house my rules" philosophy. I realise that it is your wifes house too, but she is trying to remove you from all of the decision making processes as far as your stepdaughters are concerned. If she makes it known to her daughters that they don't have to listen to you they won't. This cannot lead to any good what so ever. I could be wrong this is just my opinion.

I am curious though how you are married to someone for eight years and not know how much money they are contributing to the household.