Originally Posted by adhiren

You'd have to call Virgin to check if there is availability but theoretically it is doable. Delta deals with upgrades differently so Virgin would need to re-issue you your ticket as opposed to just upgrading you like they do for Virgin operated flights even if you're ticketed under the VS code. You can also reach them on the website through the manage my booking page - and they can quote you the price/check availability through that too.

Just to warm you Delta doesn't always make those available so I wouldn't get my hopes set high