Originally Posted by jmolony

2) I will meet the friend in the MLL - but I will have the certificate. Will he be permitted to check-in without physically having the certificate?

They can check in, but the upgrade with certificate doesn't get them access to the MLL. The have to have status or be with you.

3) Do I request the upgrade or can the passenger do it on line?

I would call if I were you just in case there is an issue.