23, and not me. At first we did the whole Toxic Troll hosts a pool party and Husband pays for toys and snacks and food and cake and pinata and pizza and drinks.

THEN we just did our own thing. I guess reading your previous post (just skimmed honestly with so much text and no paragraphing it was HARD. Just saw a few sentences here and there).

Can you give more info in paragraphs?

Typically birthdays are each to their own. This year, Backstabber/Munchkin got something I bought a while ago, and thats it, nothing from me, Ill just show up.

Early on BM and DH would have joint birthday parties for the skids.  She planned and hosted some; we planned and hosted some. DH would pay for most of it. These days BM has the Golden Goose and doesn't need any help from DH, so she throws the big birthday party that the friends and her family attend. We do not attend, and we do our own small "family" party. Works for me!

Stages:

1) early on, when I was involved; I would join the party for a while with DH either at BMs or another location or BM would come to our home. It was super uncomfortable and I noped out of this after the first one for each of them.  BM and DH rotated who would be in charge of b-days each year.

2) started arranging off-site bdays so it wasn't at our home for a couple years. SDs liked this a lot (roller skating, ice skating, art parties...) but found I was the one doing ALL OF IT. So noped.

3) Back to parties at home (SDs wanted this as they got older). I helped arrange. I helped cook or get special food and SDs always asked me to do a dessert of their choice (I am a very good baker).  BUT the dessert was invariably not eaten, meltdowns (YSD) would happen, food would be wasted.  So I left them up to DH.

4) Last party:  OSDs 13th at our home. LOTS of her friends over. I agreed to do a 'hot chocolate bar' for them. I was not once introduced to her friends I didn't know (all of them but 2), I was not introduced by DH to the parents dropping off their kids (I was getting a lot of curious looks but NO ONE else noticed and I decided to watch how it developed), and BM was there (Eff me again - of course OSD was allllll about MOM and DAD and PRESENTS. Got not one thank you for the hot chocolate or anything. It was like I was invisible. I ended up dumping out the hot chocolate, cleaning the pot (I didn't want anyone ruining it) and left everything up to DH as I retreated to the bedroom with a wine bottle. DH did get an earful the next day from me about how I was treated.

Current status:  I do not have anything to do with SDs parties, I do not give gifts to OSD since she PAS's out (about 4+ years ago) not even a card, and YSD, since she cannot iterate what she wants for gifts or give a heartfelt thank you for even cash, just gets a card from me.  I don't think she even opened it this past birthday.

My husband has attended birthday parties that BM has arranged (and he has paid for). The first time I was invited until the last minute when my invite was withdrawn by BM. I was angry about that. I was even angrier that my husband told me not to go anyway despite it being a "joint" party held in a public park so there was no way that BM could "ban" me from it unilaterally. My husband swore he would never do a joint birthday party after BM's behavioir at that party.... The next year BM arranged a birthday party at a bowling alley, which my husband paid for. My husband went because "for the kid". I begged him not to go and reminded him of what had happened the previous year. He went anyway. He had an awful time and realized that he had just been used to pay for a party for BM and her friends who apparently ignored the kids there. Fortunately the next year we moved several states away so that this has not been an issue since. 

I am happy to attend and have helped arrange parties for my SD when she has been with us for her birthday. Moving thousands of miles away from BM was the best thing to happen to me as a step parent.