Originally Posted by bocastephen

You cannot check-in upgraded tickets online - only at the ticket counter. I would caution to do the following, based on my multiple flights with BR:

1. bring a printed copy of the upgrade receipt from United - I've been asked to show it in the past, although rarely
2. if you are traveling with someone else, I suggest checking in separately and having one person stand back out of sight and hold any larger/heavier carry-on bags. Some BR agents will weigh and measure carry-ons, and a laptop with a few odds and ends can exceed the limit. I've left my bags in the car, gone to the check-in counter for my boarding pass, and then gone back to the car to get the carry on bags. It's a hassle, but much less of a hassle than dealing with the odd overzealous BR agent who insists on checking a laptop