Username update paradox confusion?

So I was creating an account to start an application to a school. I used my email to sign up for the account then once I was in, I realized that they needed my parents email in the slot, so I went to change it. I went to the “update info” tab and typed in their email. It said this is already being used but still let me update it to that. My parents already had an account with that email. So now my account is linked to that email, but is no longer accessible. But theres one problem, I had already started the first part of the application which was my general info like my name and birthday. When the weird email chaos happened, I just restarted with my parents account. However when I started filling out my info on that account it said “this exact first name, last name, and birthdate has already been submitted.” So now I can not access the old account to change it back to my email and delete it, nor can I apply on any other account with my name. I could contact the school, but I do not want to jeopardize my chances of getting accepted into the school. What can I do to fix this without deleting my parents account and without contacting the school so I can still apply?