Companion Tickets - Upgrades

I think I know the answer to this one but nothing ventured...[:(]
I've got a companion ticket burning a hole in my pocket and in Feb I've got to go to San Diego for a conference. So my initial plan was - book an S, grab a companion ticket for my colleague then use miles to upgrade my S to a G. However Premier Team tell me that both of us have to travel in the same class of service. I think they're probably right but it seems to hinge on the interpretation of
"4.4.4 Once tickets are issued, you may make a change to your travel date, route or class of service for an amendment fee (clause 4.21), except where the reward is a companion ticket and the person travelling on the paying ticket changes his or her flight or class of travel. In these circumstances, the companion ticket may be similarly amended, subject to availability of seats and other conditions laid down by the reward provider. Once tickets are issued, no name changes are allowed. No changes can be made within 14 days of travel. Once travel has commenced, date and name changes are not permitted."
It's the "companion ticket may be similarly amended" not MUST be similarly amended that vexes me...
All thoughts welcome
I've got a companion ticket burning a hole in my pocket and in Feb I've got to go to San Diego for a conference. So my initial plan was - book an S, grab a companion ticket for my colleague then use miles to upgrade my S to a G. However Premier Team tell me that both of us have to travel in the same class of service. I think they're probably right but it seems to hinge on the interpretation of
"4.4.4 Once tickets are issued, you may make a change to your travel date, route or class of service for an amendment fee (clause 4.21), except where the reward is a companion ticket and the person travelling on the paying ticket changes his or her flight or class of travel. In these circumstances, the companion ticket may be similarly amended, subject to availability of seats and other conditions laid down by the reward provider. Once tickets are issued, no name changes are allowed. No changes can be made within 14 days of travel. Once travel has commenced, date and name changes are not permitted."
It's the "companion ticket may be similarly amended" not MUST be similarly amended that vexes me...
All thoughts welcome
