Generally, agents in legacy airline lounges (e.g. a United Club, Admirals Clubs, etc.) are willing to do things like this.
Anecdotally, I've noticed that they tend to be more senior (so know what's possible / what they can get away with), less busy (so they're less frustrated and frazzled), and tend to deal with much more experienced travelers than a normal gate agent (so, again, they're less frustrated).
Anecdotally, I've noticed that they tend to be more senior (so know what's possible / what they can get away with), less busy (so they're less frustrated and frazzled), and tend to deal with much more experienced travelers than a normal gate agent (so, again, they're less frustrated).