Calendar synced to my parent's iPhone

I have been trying to figure out how to separate my calendar app from my mother's, but nothing is working. Anytime I input an event into the app, it switches to appear as if she wrote it and simply invited me. I see all her events and every single edit she makes (not just the things she 'invites' me to). It's been years and been fine synced but I'd love to have separate calendar accounts now. But checking my icloud account, I dont see her name listed anywhere so I don't think it's a matter of us sharing an account as much as mine being confused as hers. But ALL my other icloud systems (photos, contacts, etc) are mine independently. Its just calendars that for some reason wont separate. (I've also tried deleting the app, re

[Re-Titled by Moderator]