I actually had a TP issued ticket on 047 stock originally issued in V and purchased on Expedia. I upgraded on Lufthansa.com and from then on the booking showed Z class everywhere. Expedia even notified me that the airline had changed my cabin. The 1250 miles credited to A3, who also showed Z class on the statement.

I should point out that this was no cheaper than buying a Z fare in the first place, except none of TAP, Lufthansa nor Expedia were technically able to offer a TAP Economy out and Lufthansa Business back ticket.