Need advice from Step Fathers/Fathers please

I have to say yes, I'm both, so I know right where your at. as it has been mentioned Make "no" mean, NO and be sure "yes" means YES. NOW the key, is to interact with the kids and when something is "in-question" speak with your girlfriend about whatever issue it is, compromise if you have too just a bit with HER not them. you need to set that example, and once they "the kids" see, and feel this, it will teach them that, we can't go to you for one answer and Mom for the other..

AND NOW, because this sounds serious (I got input there too) I married the girl so. my now wife, first wife but anyway, this opens up a door for you to have your "own" not step-kids. with ALL of them should that happen, treat them the same, "no" means NO and "yes" means YES, and anything in question talk with her on it and come to an agreement. all after this should turn out well.....

The best advice I can give you is TALK TO HER on EVERYTHING even the smallest detail! Specially raising kids. you want them to be the best person they can be when they're grown! That is where the 2 of you, have to set that example!