As long as you and BM can get a long things should go smoothly. Even if you are "co-parenting" I would be careful about watching boundaries. I have discovered that even when BM asks me to do somthing that when I do it, she views it as over stepping my boundaries. Not every BM is that way, I would just suggest making sure that the "rules" are very well laid out so there won't be a miscommunication. Good Luck.

I would be very cautious about having a best friend relationship. Keep in mind that there is a reason that your husband and his ex divorced. Your husband may not want to see a lot of dealings with the person who either asked for the divorce, or gave him reason to ask for the divorce. I tried to talk things over with my husband's ex after several years of them fighting over everything. I thought things were fine, but the reason that she pretended to be my friend was to try to get evidence that would allow her to get custody of my SD's. After one incident that my oldest SD ran away, I was blamed for my SD's emotional pain, and the ex decided she didn't want to be my friend anymore. It didn't matter that I was not involved in what my SD accused me of. So, all that to say, just be careful as to how friendly you get.

Being married to a person and co-operating with that person to help raise that persons children is by far two different things.

I think its great that you two ladies want to keep things smooth for the children. You are doing what so many step/bio parents seem unable to do: Put The Children First.

I think the best rule of thumb would be to let the bio-mom be the final authority on rule making.

I'm basing this on the assumption that the kids live with the bio-mom and visit with you on weekends and such.

I.e. if the two mom's disagree on a rule then the bio-mom's rule stands.

Am I correct that the kids hate the bio-moms new spouse? Well there's not much you can do about that. I would sympathize with the kids if they complain and make suggestions to them about how they can get along. But always be careful not to undermine the bio-mom and her's spouses authority.

My advise to the bio-mom's spouse, the step-father, would be to stay out of his step-kids life as much as he can. He'll never win them over and its useless to try. Just stay neutral.

I don't see any problems that cannot be overcome. Just deal with them as they come along.

I would suggest asking your DH first, on how he would feel about the idea. He may have suggestions of his own to make. I don't think that the two of you should exclude him, from any "laying down" of the house rules.

I would suggest a meeting with all four of you. Talk about the situation, and get everyone's input, on how they feel the rules should be. That way, all of you are on the same page as far as the rules go. If one of the kids doesn't adhere to the rules, then all of you are on the same page, and can discipline each child accordingly.

Afterwards, you can include the kids and tell them about the rules. Let them know, that all four of you are the same page. One parent will not slack off on the rules, while three of you enforce them. Lot's of times, kids try the "divide and conquer" scheme. As parents and SPs, you should show a united front, if possible. You are lucky enough, to have a pretty decent relationship with DH's ex.

I know from my own experience, that what you two want to do, would never work with my SS's BM. She hates the very ground I walk on, and I've never done anything to her. I'm only guilty of loving her son. That love, is something that I am not ashamed of.

Tread carefully, this will be a very delicate situation. Good luck! I hope my suggestion has merit.