Yeah they're both Jujamcyn so I'd imagine they'd have a similar policy.
When I went to the box office, I brought the original tickets and the receipt. Good luck!!!
The first question they asked me was where I originally bought the ticket. If I answered Ticketmaster, I have a feeling they might have forwarded me to ticketmaster to process the upgrade; but since I originally bought it there at the box office, they were able to make the changes no problem.