Have you needed accommodations for being plural? (Whether for specific system members or for the system as a whole.) Do you have advice on asking and advocating for those accommodations?
I also have ADHD, so me forgetting things is...frequent enough already. So, at work, and with my roommate (neither who know I'm plural), I've said/asked for accommodations relating to memory stuff. Like "Could you put that in an email? So I can look it up later" or "If I said I'd do the dishes but then I don't, it's not me trying to get out of doing it, I just honestly forget, so pls remind me and I'll do it."
You can forget stuff for tons of non-system reasons. And if you're asking for accommodations at work, you can say "I have a medical condition that affects my memory, so it would help me a lot if you...". Or even just "I have to juggle so many projects, it really helps me if you can put that request in an email, so I can organize my tasks" or something like that. In a work environment, it is best if you do not give details about your medical situation (and this includes mental health stuff), because it's not anyone's business what you have going on. It also looks really good if you say "I am doing these things to ensure that I do not forget things," because so many people don't bother with stuff like that. Being aware of your "flaws" and doing what you need to to "counteract" them is something good managers always want to see.
When I figured out I was a system the other month, it was really rough mentally. The physical symptoms of it were really bad (headaches and all that) and it was just mentally exhausting. And then my bicycle got stolen, which is how I get to work, so I did tell my boss that, because I needed to miss a meeting so I could deal with that (reporting it to the police etc). And I ended up using that as an "excuse" to take a couple days off work, because I, truly, was at my limit mentally and I NEEDED to stop working/have expectations/things to do so I could sort everything out. So I did say "I need a couple days to sort stuff out this is Mentally Stressful" and my boss + coworkers understood.
So if you are ever having a tough time and need to take time off of work (and your job doesn't have a bad policy that forces you to get doctor's notes), you can be vague. "Hey, I came down with something, I think I'll be out for a couple of days." Also don't forget to say "I tested for covid so it's not that, don't worry" so people don't get concerned they need to test, too lol. If they ever want specifics, for whatever reason, it's easy enough to lie and say it's food poisoning or the flu. "I don't think I'm gonna be in good enough shape to answer my email, so I'm just gonna disconnect and focus on getting better."
I don't have any advice on how to get accommodations for school, since I have no experience in that. And these experiences are based on office jobs in the US. It might not work in every situation, or you might need other kinds of accommodations. Also sorry if this seems like I'm approaching it from a medical-y/disordered approach. Asking for/getting accommodations at work/school is based around medical conditions/disability, so framing your needs as "This is because of a medical thing," it implies this isn't something you can "fix" by trying harder or whatever bs people tend to say. And you don't want people at work giving you crap for brain stuff.