I just did the exact same thing this weekend. In my case, there was an added level of complexity that may or may not be relevant in your case.

My friends were flying EWR-LAX on Tuesday. On Friday, I called United to add the upgrade and was told I'd have to go to an airport or CTO to authorize the use of my e-NA. On Sunday, I was at SFO dropping off friends. As of that date, I was told that the upgrade hadn't cleared and thus they couldn't take my upgrade yet. Basically, they said they wouldn't start clearing names from the list until 1 hour before departure. This would have required me to run off to the airport at 7 AM Tuesday if they cleared.

The agent checked with her supervisor and informed me that they could take the e-upgrades and then redeposit them if the upgrades didn't clear.

Tuesday AM, my friends show up at EWR. The upgrades have cleared, but they actually have *not* taken them from my account. They had to give the agent my MP number for the transaction to go through.

So moral of the story is that if the upgrades haven't cleared yet, you may have some issues to straighten out. Make sure your friends have your MP number and stay by your cell phone around departure time.

cnk