I really don't want to end up in a situation where I sharing a birthday with my kid causes resentments in them or bonds with them that exclude either of the kids though. I... need to figure out how to walk that line...
You are looking way too much into the future. Even if you manage to walk that specific line, there will be countless lines you won't walk, mostly because you won't know there's a line, so I suggest you take a slightly more laid back approach, you simply can't juggle all these balls at once, better accept than some will fall. This one isn't anywhere near the most important in my humble opinion, mostly because there's little you can do about it. It's just a date.
Oh, don't worry, I'm not like, obsessing over this. I just always want to think about my kids a lot. And think about their specific things. and how life works. I care a lot about my kids, and I want to make sure I am doing right by them.
And I definitely don't show my kids these anxieties, at least not usefully. and @Becky would tell you I'm already way too laid back ;)
I wanna make sure I have the pieces in my head, so I can have the prep work done, so that I can keep being a firm and kind foundation for the kids.
@silverwizard Well two of my kids have not contacted me in 12 years, one of them is still living at home at 31, only one has really applied himself AND stays in contact. They might be doing their own thing but could be a bit more communicative.