The child's Christmas concert is probably not the best time to start digging your heels in. You've had plenty of occasions by the sounds of it to,start setting your own boundaries, for example BM popping in unexpectedly when you have SS. All the phone calls to BF etc., I wouldn't be using the child's concert to start something. If you are uncomfortable then just don't go. Explain to your boyfriend why yue uncomfortable, and politely bow out without fighting with bf over it or demanding your way over it.

What I don't really understand is this. You say you don't have any real issues with BM. You are not bff's but there is no open hostility either. Why would you want to start open warfare with her. Why would you want to bring that into your life.
It's a Christmas concert, it will be an hour or two, you don't need to go out for drinks afterwards, you don't need to be chatty with her during the concert, you're supposed to be watching the concert. If no one is making you feel unwelcome or unwanted, why start something that could lead to friction between you and her.

Your boyfriend is going to see that his ex wants to get along with you, happy to have you attend the concert, and you are the one causing problems and refusing to sit with her and her boyfriend. Why?

I know the vast majority of stepmoms here will tell you you're right, stuff her etc. the vast majority seem to think that sm and BM should never get along. That their husbands/boyfriends need to hate the ex. It doesn't have to be that way. People grow apart, divorce and can be mature enough to get on with their lives without hating the ex. If children are involved this is particularly important.

I think you attending the concert and changing the seating arrangements from the usual mom and dad sitting together which seemingly has gone on for years, to her and her bf sitting in one part of the room and you and bf another is unnecessary, and unfair to SS. It will be picked up on by BM and it will create tension. SS will feel that. As will everyone else. Why do you want to be the cause of that.

You and your bf need to discuss boundaries, phone calls and whatever else is worrying you and work it out between you. But SS concert is not the time or the place.

Tell him ONCE that you're not sitting with BM.

My mom has a saying~ I can show you better than I can tell you. Don't waste time discussing it over and over again. Say what you're going to do, mean it and stick to it.

When you get to concert, sit where you want and let BF decide where he will sit.

Standing your ground on this will show him that he can't talk you into doing anything concerning BM that makes you uncomfortable.

having been in this situation a few times with my ex and his wife as well as with my SO and sd, bm I can honestly say that I think that you are linking the situation about boundaries to this one event. It doesn't really need to be like that.

For one thing, this is a separate event that is solely for the purpose of going to support ss in his endeavors.

I personally understand you not wanting to sit with them. I usually let it play out on it's own. When both my daughters graduated (one from high school, the other from college) we just played it by ear. Actually, my ex just sat with his wife across the stadium from us and didn't try to sit anywhere close to us. I didn't try to sit close to him either. It is too hard to save seats to me at that sort of thing.
Possibly at the same thing you're going to it will be hard to save seats as well, so maybe that serves as an excuse.. just sit where you have a seat available.
One time we went to a dance recital for sd and we sat with my SO's family and bm's family sat on the far side away..but just by chance. We didn't go out of our way to sit with them.
We went to a church function and they sat up front. We sat in the back. My SO went to a church function and sat with their family. I wasn't too cool about that as bm's spouse was out of town. Rent a spouse night.
Like you said.. it's my SO's responsibility to keep the boundaries in place!!

I don't see a reason to present a united front. SS obviously knows they aren't together. Who does she thinks she's kidding.

As the first commentor stated.. this is not the time to dig in your heels. Just go with the flow if you can but you need to sit down aside from this situation and have a long talk with your bf about your expectations and his expectations.

If the guy doesn't care to change it or to adjust the boundaries, they will never change. Now you resent the bm but eventually you'll resent ss, too.
And like you pointed out..it's your bf's fault. Not theirs. To be the devil's advocate here.. he will most likely respond that it's all worked well so far and why the big change up? it was all good before you got in the middle of it. you need to be prepared to hear this as some point!!

Good luck!! Don't sweat the small stuff!!

Perfect! You sit next to her make sure you push your way through first haha - and look past her and constantly exclaim to her BF "awww, isn't Skid just the cutest?!" Haha Go fuck with them! Haha

I agree. If I your not happy or you are uncomfortable, don't go. But tell him the truth, don't make excuses , don't blame anyone. Just tell him it makes you uncomfortable and you feel,awkward about sitting next to her, then see what he does about that.

Ultimately your boyfriend needs to be the one who sets boundaries here. You need to have input as to what you do and don't feel comfortable with. None of this is SS fault, though any drama at the concert, and he would be collateral damage. None of this is BMs faults. She owes you nothing, she doesn't have to like you or respect you, but your boyfriend, well he damn well should be putting her well and truly in her place if she doesn't. Your boyfriend needs to listen to how you feel here, and respect your feelings. You need to be honest with him about your feelings. But as I said before, this Christmas concert is not the time or place.

we dont even sit with BM, well none of us ever speak to eachother (not our doing)... BM likes to pretend we dont exist, even at exchanges. Yeah the kids can't feel that hostility or anything! She just hates DH and me bc he got residential custody- she still feels the kids were wrongfully "taken". ANYWAY. I agree with everyone else, You dont have to sit with her, if DH makes a deal about it, dont go. The kid doesn't care if you are sitting together, he cares that he sees your smiling face.

This issue aside, you really need to get with DH on these boundaries. You are not happy, and that is not acceptable.

Not having read the other responses this may be a duplicate. Your BF is not going to change. He has made this clear by simply ignoring your stated concerns. His child and his mother are more important to him and who can really argue with that?

Be very glad you're not in the middle of WWIII with this woman. Just read the other threads on this web site to see what you're missing. I would make it clear that you're not sitting directly next to this woman.

Normally gentlemen will sit on the outside of the two woman with them so the women are protected from strangers sitting next to the group. Tell your boyfriend that he is to sit with either his ex or her boyfriend on one side and you on the other. (You would prefer a stranger on your opposite side as opposed to having her next to you).

Or if you want to have some fun sit with a stranger on one side and her boyfriend on the other. But don't be surprised if his leg keeps rubbing up against yours.