Adding two tickets will be a little tougher than moving sections.
In the ticket renewal process, you can fill out a form and request to move your seats.
To add seats to your account, you'll have to wait until everyone goes through the renewal and relocation processes. Once everyone else goes through that process, you'll be able to add more tickets to your account.
I got additional tickets prior to the end of the season to avoid that process and will just relocate mine to all be together through the renewal process.