I know were not allowed to have more than one account per person but can my siblings make accounts from the same computer or am I the only one allowed to make an account...

I would file a ticket to let them know that you & your siblings have accounts that come from the same iP address c:

My brother just made a Subeta account as well. You should file a ticket in "Account Issues -> Other" and just let them know that your siblings have signed up and what their usernames are.