Thanks for all the responses. I apologize for not being clear I was ranting & in a long drawn out discussion with DH about this. I wish I could use the business trip excuse but its a company picnic at an amusement park. Its a day trip were no really business will be done. My SD is 10. I transferred all the activities in my phone calendar and destroyed my physical calendar (which is much more helpful to visualize) to avoid her crashing anymore events. It is hard because we do Sunday dinners at my parents house. My younger sisters talk about plans every Sunday. It's hard because I don't want to silence them or have them running around to whisper behind SD's back.

I'm mad that SD is beginning that phase that she runs behind everyone's back to get her way & BM facilitates it. (Not saying its bad. It's typical for a kid. I remember asking my Dad to do something, getting a no & trying to get a yes out if my mom). It needs to stop because she's only 10 now, and its minor stuff. She should not have crashed the party. She has already asked BM to shave her legs and got a no. She told me it happened. Then turned around and asked DH and he said yes, SM will show you how. I had to explain to DH and SD that BM already said no and no is no. She's not going to circumvent BM on my watch. At 10 she's not smart enough to know not to tell my BM already said no. We're getting to the point where she's knowing how to get her way and it needs to be nipped before its seriously things like boyfriends, sex, and alcohol. (Well BM let's me drink, when she doesn't.)

Thanks for the response. I was ranting in my post. The issue is when SD did this to BM, chose to want to live with DH full time, BM flipped out & filed for custody (we were operating on an EOWE no custody order schedule prior). She claimed to DH that she can't make her own decisions, so we have to get a custody order so she can't do this to either one of us. Makes sense. The problem is we do the right thing. Custody order was just signed by the judge. It's 50/50 and any family events will be accommodated by the other party with advanced notice and time proposals on how long we will have SD and when the other party's custody will resume. SD runs the show with BM. She called during our last custody week and SD told her cancel my hair appointment, I want InNeedOfGuidance's mom to cut it. (My mom is a hairdresser). She didn't ask me or my mother if that was even a possibility. I demanded that DH contact BM and make sure that this was okay because it's not SD's decision to make. BM told him it was okay, but I didn't get the impression that it was so we agreed that if she came back with long hair then BM was really okay with the free haircut and my mom was already on board to do it. BM cut her hair this week, which tells me she wasn't okay with it but won't say no to SD. I know she doesn't like when these things happen to her, and I do everything in my power to make sure she's not unilaterally overruled by SD. I just want the same courtesies. She knows how it feels to be powerless. SD has taken that power from her more than once. It doesn't happen on our watch. It shouldn't happen to DH & I on her watch.

As far as the trip, she went last year when it was her weekend. (First time in almost 5 years it fell on her weekend). She simply invites herself along and BM approves it. I agree that communication needs to be better between the two of them. I and DH have done everything reasonable to assure that SD isn't running behind BM's back and dictating . BM just allows it, and I don't know how to cope with it. To me, if BM left the soccer game and SD told me she was allowed to go to a party for BM's cousin, I would have told her no or confirmed with BM that it was true (otherwise BM would have stayed to take the kid with her). It is more a matter of not letting a 10 year old run the show. I live having her around and truly do love my SD. I always strive to do what's best for her or what's in her best interest. I was drinking at this birthday party. My whole family was drinking (not drunk as it was the middle of the day) but I don't drink in front if SD. I don't spend my time with her glorifying alcohol (I.e. drinking looks fun). I was certain she wasn't coming because we made no arrangements for her to be there. Sorry for another rant, I just feel that dropping her off whether she lied and said it was okay or not is irresponsible & perpetuates this manipulation that can not continue. That's why I place some blame on BM. She wouldn't appreciate us dropping her off when she had other plans because "SD said it was okay to go home and work on x." Luckily in this situation DH wasn't drinking, but we occasionally plan bonfire/drinking parties at my sister's where we park the car for the night & crash in the spare room where we have no way to return SD home if she's just dropped off. Additionally this custody order is enforceable by police, by order of the court, and there's no limits to BM, she called the police without a custody order before. Therefore just to protect ourselves, this cannot happen.

SD was nosing around my hanging calendar looking at what events I had planned so she saw the trips were planned. I don't make plans for these trips. My parents do it. The one is scheduled by my dad's employer and the other is scheduled around my sister's college schedule (she's at a D-1 school do we schedule around home football games do she doesn't miss a game. The issue isn't so much whether we want SD there. Myself and my family include her in everything. The issue for me is more that she noses around and feels entitled to be included in everything. She threw a hissy fit (threw herself on the ground crying) that my mom, sisters, and I went to the movies during my youngest sisters spring break (which fell on he off week). We didn't include her (when she was at BM's). It's making me like I am right now. Had SD known about it BM would have just dropped her off. She knew about this party because of the calendar. She was reminded if it when DH dropped her off at BM's and was talking to SS20. SS works where they were throwing the party & DH was asking SS if he was going to be working. Nosy SD was listening in on the conversation. SD had ample time to ask to come, and we more than likely would have discussed it with BM and accommodated it. Instead she shows up to everyone drinking and there not being a chair at our table for her. I had already advised my extended family that she wasn't coming. So in essence a 10 year old crashed a 30th birthday party.