I for one won't be doing any joint parties with BM for SD ever. We did two and she acted crazy after both of them.

DH can do whatever he wants but I won't be there and neither will our bios. I refuse to expose them to that loony lady. No matter what SD wants.

I know I sound like a wicked step mom but I swear I tried already and BM is just crazy and will never change.

I hope ur DH can shut this idea down no problems

All I can hear in my head is "don't do it don't do it don't do it" lol

High conflict BM is a high conflict BM, no matter how well she may behave for now. Doesn't mean you have to be rude about it or start a war (though she may anyway). But a polite, "thanks! but no, we're getting along so well now that we're keeping things separate, let's just leave it alone" SHOULD be innocent enough. And if it isn't, and she snarls, you'll know you were right and she hasn't changed = yay you dodged that bullet.

Plus, since she wants you to pay half, I see ulterior motive. Take your "half" and do something special for SD if you like.

Once you agree to a joint party it NEVER ENDS. Don't do it!

I see a few options depending on what you want to do:

1. If you decide to do joint then BM pays for all her invited guests and DH only pays for his guests.

2. No joint party just let BM do her own thing at the restaurant. Then DH could let SD invite a few of her friends to do something special when she's on his weekend. (My preference)

3. Or try this one haha have DH tell BM "Sure we can have a joint party, I'll plan it and I'll bill you so you can pay your half!" (BMs do this all the time so why can't a BF do it too?)

We went to SDs 3rd B-day BM planned because we were supposed to take SD7 home with us after the party (per the CO) When we got there BM tried to get DH to pay for half even though we didn't invite anyone and BM had about 30 guests. Laughable! When we were leaving BM threw a fit to show off in front of her friends and family when we tried to take SD home with us. Rather than make a big scene (we could have called the cops to enforce the order, we've done it before) DH didn't want SD to be put in the middle on her birthday of all days, so we just left.

Hugs! Good luck and hope you find a four leaf clover! I agree 100%. We told SD that it is a mom's job to throw a sweet 16 (at least that's how it is here). Just take her and one friend to a nice lunch later or have a paired down DH family party announcing that BM's sweet 16 was a success. Sorry, but DH already paid BM for SD's sweet 16 at BM's house with CS. My skids BM wanted to go halves on a puppy! A PUPPY! This psycho doesn't even like dogs. Disney Dad almost said, Yes. Until the wicked stepmom (me) said, NO WAY! WE have enough of our own dogs. Do you know what it costs to take them to the vet? get them spayed? Feed them? No. because that is my job. She needs to have her own stuff with her nuclear family (mom's house) and she can pet our dogs when she comes over. She brought her dog here once! Once and only once! Who do you think house trains them at BM's house. That's right! Nobody!

Oooooo.
Bad idea.

I was recently put into this very same situation. SD 15 will be turning 16 in a few weeks and back in January, DH approached me and asked me to assist him ( which really means me doing the actual work part while he finances)in putting together a modest Sweet 16 party for his girl child, much like the graduation party we did for her brother last summer, since her mother said that she wasn't going to give her a party. I agreed, as I enjoy the challenge of putting together an event on a budget and I plot every detail like a general going to battle. My parties rock.
We secured a venue, hired an old friend who happens to be a DJ at a huge discount and had decided on a menu and total number of guests. Am not exactly sure how it all transpired but I received an email from BM one morning, thanking me for offering to 'help' HER put this event together.
Say what?
She mentioned that she could not afford to spend much money and was happy that we 'agreed' to split this expense with her. I just looked at my ball-less DH and said nothing as I'm sure he mentioned what we were planning and she steam-rolled her way in.
Because I have spent this relationship trying to be a bigger person, as DH tries to co-parent with BM for the best interests of the children, I agreed to do my part, which consisted of the details that I had already secured plus catering the food in my own kitchen to save money and BM would concentrate on the 'fluff' part such as dress, cake and decorations. I had the best intentions.
BM absolutely insisted that SD have input on this event and I began receiving daily email updates from BM on all of the extravagant extras that SD wanted, like a chocolate fountain and round tables instead of the long banquet style ones that were included with renting the hall of the local firehouse. She wanted a different venue as SD's 'court' needed to make an 'entrance' and she didn't like the firehouse. The guest list suddenly doubled with the guests that BM wanted to invite and this all coming from someone who said that they could not afford to spend very much.
The lightbulb turned on and it occurred to me that BM was trying to throw this grand affair completely on our dime, leaving it to us to do the planning, labor and paying while she works the party and acts like Mother of The Year to all of the guests, so I did what any sane person would...
I sent an email right back and very eloquently explained to her that because she was clearly struggling with allowing us to share this event by not staying in her own lane and because we clearly weren't on the same page as far as expectations that I was going to disengage myself and allow her to plan and execute this party alone as she saw fit. Since she didn't approve of my venue, I got my deposit back and since the DJ was doing ME a favor, the discounted rate would no longer apply. I had DH's blessing, thankfully, as he saw her trying to manipulate the situation but for whatever reason did not call her out on it.
I let the issue go. As I saw on someone else's post the wonderful quote that applies here: " Not my circus; not my monkeys. "
I asked DH a few weeks ago how the party planning was going and I found out that BM cancelled the party completely since she couldn't do it by herself. If she didn't get greedy with other people's generosity, this event would still be going on. Way to GO, BM... Building that child up just to snatch it all away. No wonder she has issues.

SD15 is back to ignoring me as she has for much of the 4 years that DH and I have been together since I didn't bend over and grease myself while allowing BM gold card access to our finances for one day of glory...

Am using that $$$ to go to the islands next year instead. With NO kids.

Don't do it. It won't end well.