Special consideration and extenuating circumstances

Can universities find out whether a candidate has applied for special consideration? And therefore shouldn’t fill out an extenuating circumstances form for the same reason. Or could you just do both? Also, if I tell the admissions team about a mental illness and provide evidence for it, will my department at university know about it? Like who at my university will have access to the information?

i believe universities aren't made aware of it so you could perhaps do both, i have seen some saying if you've applied for special consideration they won't do anything on top of that. If you tell admissions they'll probably direct you to student support who would share that information to your department with your consent.

Thanks a lot for your reply. If the universities don’t know I’ve applied for special consideration why won’t they do anything of top of it? If I don’t want to share the information with my department would that be ok? Or do they need the info in order to determine places? I would want the least number of people to know about it as possible.