When it comes to companion upgrades at the gate, it's up to the GA. A few told me "no" in MSP last month (I was asking other GAs as the one for our gate had not yet arrived). Luckily, the one that ended up working our gate said no problem and upgraded multiple companions.

I think it's a pretty short-sighted GA that refuses to upgrade an extra companion for a PE and then lets F go out half empty. Perks are what keep us flying NW!