Agh. No. Just tell SD that you will carry on having two separate parties and that lots of divorced families do that and don’t have joint parties. Give examples if you have some, of her friends who are from divorced families. She will get over her disappointment.  BM just wants a venue for playing MOTY, and she will slam DH no matter what he does, so do what you guys think is best. 

The only way to win is not play the game. This year, I would go. Next year, I'd plan something for SD and tell her to bring a friend or two.

This is what we have done with the boys. Whatever visitation day is closest to their birthday we plan a party with family. We ask if they want to do something and if they want to bring a friend. They are usually content just to spend time with DH, and they usually want to see a movie or go to a trampoline park or go to a comic/gaming convention for the day.

We don't tell BM that we're planning anything. She just assumes now that it happens. That is perfectly fine with me and it means she no longer plans extravagant parties expecting DH to foot the bill (because he just won't show up).

BM thinks she has your DH by the balls. And this year, she does. Next year, go back to individual parties. Or, if you have time, plan a party this year since your DH has every weekend available. He can tell BM the following:

"Sorry BM, we won't be attending. I only agreed to a joint party if it were at a neutral location, which it's not. I will make plans with SD. Good luck."

Then IMMEDIATELY tell SD:

"SD, I offered to host a party with your mother if she planned it with me, and that didn't happen. We will celebrate your birthday with you the weekend after. Until then, think about a friend you would like to invite over that weekend so we can do something fun for you."

It's perfectly fine to tell SD the truth of the situation, especially if BM is going to lie about it. 

I wouldn't have taken days off. just simply plan a party for SD. Tell people about it and leave it at that. Even combo parties in a neutral location doesn't always work out. Take SD5's birthdays for instance. We tried a combo party, at a park. nice neutral location. Psycho made it all about her, made the kids uncomfortable, everyone else uncomfortable. And everyone hated it. So we decided no combo parties. Then we throw SD5 a birthday party this last year and she shows UNINVITED. Again makes it about her. Keeps pulling kids off of things (trampoline park, I paid a million dollars SO THEY COULD JUMP), taking pictures, then proceeds to take credit for a party SHE WASN'T INVITED TO.

Neutral location doesn't always mean a good situation. She sounds high conflict. I would avoid even a bit of combined parties and go for two seperate ones. No need to encourage her insanity.

whole situation really isn't a joint party. It's BM throwing a party and making everyone go along with it. I mean, you are all supposed to be cohosts but you didn't know the location, the date or the guest list until the royal summons was delivered. Looks like you got bamboozled and it's well within your right to say no. 

If your DH keeps saying "it's only for 2 hours" or "it's for SD", ask him how he's going to handle it when she thinks that you'll always be willing to play happy family with BM. What happens when the invites stop including you? Alternately, what happens when  SD gets her hopes up because of loose boundaries and is crushed when the wedding happens and a new household with boundaries is formed?

Your SO needs to pull his head out of his butt. He's trying to build a life with you and SD, not BM. They had their chance.

This reminds me of the annual call from BM that my DH used to get... "demanding" that he give her money so that she can buy the girls christmas gifts.. every single year he told her that she didn't have to buy their love.  The reality is that if he did give her money the likelihood that it would have been spent on presents for the girls was small.. and even if it was.. they would never have been told that their father was giving them the presents too.  So, he didn't fall for it.

This party is the same... it makes it appear that BM is the gracious hostess and dad is at best a guest.. not a co-host.

i also agree the girl is old enough to start having a different type of birthday celebration.  I say you can get out in front of it now.  What you do is tell her that you have a huge plan for her for next year.. you are going to take her and 3 friends to the "great wolf lodge" (it's an indoor resort/waterpark where they can stay overnight).. or we are going to book a hotel with an indoor pool and go night bowling.. or to the jumpology.. or whatever local fancy entertainment she would find attractive.  Renting the hotel room or going to a resort for a night is kind of "extra special" and the thought of having a more grownup outing with her friends should be uber appealing.  Talk it up.. bring it up with her and get her excited... but make it clear that you are doing this for her because she is old enough to do something more grown up than a cake party with family.. that you will of course have a small family dinner with you and her dad.. but that the overnight excursion is her "big" party.

BM has the upper hand and will always win.  I would not kiss a** and not show up.  Or you will be kissing a** your forever.  Have a separate party, even it it’s the three of you, doing something fun, or a fun restaurant.  

Unfortunately this is a RED flag in your relationship, your SO is not having your back.  SD has to understand that her parents are not together, and things work differently.  Or your SO will be at BM all the time. Birthday, Christmas, Thanksgiving playing HAPPY FAMILY with his EX and DD

BM over here tried this ONE time, invited us, and DH's family, to a birthday party for SD, knowing damn well that DH did not want to be in the same room with her (BM).

We did not go. We did not pay for anything, either. And, God love my DH, he did not care if he looked like an asshole. His family knows how he feels about BM and if THEY want to be wishy-washy as far as she is concerned, that is their problem.

We handled SD's birthdays on our time, our way.

I was married before and my exhusbands first wife was the same way. Insisted on joint birthday parties sitting with us at kids sporting events making small talk would call my ex husband over ever little thing. Anyways how I handle the meddling B--tch is I would go to these "joint events" looking my finest be sweet as pie with a big smile on my face being chatting and social with everyone having a great time. Pissed her off to no end. I loved it as she would expect me to not show up of be all uncomfortable. I'm SO THANKFUL my current husbands exwife HATES him and wants nothing to do with him. They don't even talk what little communication they have is done by text! Its great.

There is nothing wrong with SD having two parties/celebrations for her birthday. Do not allow BM to dictate what she thinks is best and how you should celebrate SD's birthday. If BM wants to have a party by all means let her and you and H do your own thing with SD. It won't be the end of the world and you'll celebrate on your own terms. This is a good way to create boundaries and unblur the lines of separation.

You are being emotionally manipulated by the ex.
There is no reason skiddo can not have two seperate birthday parties.
Give in now and try to please the ex and you are on a downward slope to dancing to BM's tune.
Not worth it.

Welcome to your future hun. Everything SD related will be dictated and controlled by BM. Also the extended families are sucked in and your DH taking time off of work for several days just in case BM plans a party for that day.  Sounds like the beginning of a crappy relationship where you're just going to have to go along with everything. I always wonder why people like BM and your DH got divorced in the first place.  

As cringy as the idea is for me...I would go to the party. Birthday parties are about the child and it would probably mean the world to SD that all her parents and family members are in one place to celebrate her. Perhaps you and BM could discuss alternating each year who plans and organizes the party. You could always still maybe do something special with just you, H, and SD...like take her to her favorite place or a movie or go buy a little cake and have a special night at home to celebrate her. Make your own little tradtion with her that doesn't involve BM. As far as other holidays, you have more ground to decline joining those celebrations. I wouldn't worry about that. Other holidays aren't centered around your SD. Good luck to you whatever happens.

Split the party no way i'm celebrating together like we are one big happy family. Same for holidays they are to be celebrated seperately. You aren't married yet start setting your boundaries or they will get blurred as time goes on. What if later on you have your kids will your future kids celebrate jointly because poor SD can't be upset.

"BM, however, would plan her party on days that DH is working, tell SD that she invited DH and she can't understand why he wouldn't want to come to her party."

This is a classic move that BM over here used all of the time, in one way or another. Except, she would go as far as to tell SD that her dad obviously did not love her (DH heard her tell SD this on the phone).

Bowing down to BM will not stop the alienating. People who would do that to their child, will do it regardless.

You go to the party radiating happiness on  your FDH's arm, you rock  your best look, go to the salon/spa for a complete makeover, go to your favorite boutique and get a great outfit and you walk into that party beaming how happy your life is.

Cockroaches hate light and scurry for a dark corner when the light is thrown on. Be the light.  The roaches will scurry.

Periodically lean over and whisper something naughty in your FDH's ear in order to drive a reaction that will keep the masses guessing, throw your head back and laugh.  Focus on the birthday girl but do not tolerate being ostracized or ignored.  If BM pulls any shit... bare her ass with an appropriate comment like "Wow, someone needs to get laid!" Or some such other appropriate comment to highlight BM's BS behavior.  If BM loads the Skid's B-day party with BM minions, be ready for them too.

Most of all... have fun baring their asses.

I would go and give it a try.  DH and his family are going, SD is excited, and it might not be that bad.  Be sure to look like a million bucks that day and enjoy being the better person.  If it all goes to hell in a handbasket, then you tell DH (and he can tell SD) that there will be only separate parties in the future.  If it goes well, then it's a win.

When my SO and I started dating, *everything* was joint with BM.  He and BM in their first year of separation had had joint birthday parties, joint holidays, joint excursions to the zoo, etc.  Theirs was an amicable divorce, and she is a planner while he is not, so he kind of piggy-backed on what she did.  I put an immediate end to all of that except the joint birthday parties.  Each kid still has one birthday party for both sides of the family and both sets of friends, and so far it has alternated between BM's house and our place.  The kids like having everyone there, and SO and BM don't interact more than is required to be polite and cooperative.  It's not bad.  Would I prefer not to ever do anything with her?  Of course.  But the joint parties are bearable.  Caveat:  BM here is sane.  She can be a bit controlling, but she doesn't have any personality disorders and she has the kids' best interests at heart.  That makes a big difference.  You'll probably learn a lot at this birthday party and can plan accordingly in the future.

Last year DH had SD birthday party at a skating place and BM decided to step in and took care of the guests list, the cake etc... I didn’t know any of the people that were invited apart from DH parents, I made sure I looked good, put on my happy face and showed up, at first BM was all over the place taking charge of everything and talking to everyone,  I knew she was doing some of those things to get to me, but it didn’t affect me one bit, I kept having fun, and later she looked so sad and miserable 

Go and look SHAMAAAAZING. 

I would go, and next year revert back to old way of 2 separate.  It will honestly be just as awkward for BM as it is for you... and she will quickly realize that, Lol. 

My exH has always insisted on joint parties.... and I am a pushover.. I can tell you for certain it was awkward as a BM having your ex his girlfriend/wife there and all of his family- and we are actually all friends and it was still awkward!! I bet this is the last time this happens. Lol.