Will have to wait and see what the finale language says, but to my understanding, on your “line” month while job sharing, you get paid for the fleet/seat you are actually sitting in. So for your 6 months in the building, A320 CA pay.. but if you elect not to actually upgrade or can’t hold the left seat on the fleet you teach on, you get normal FO pay for the month you go out and fly.

I mean think about it, if you would be a high seniority FO during your line months, and could get paid your CA rate at the same time, why would you upgrade and get garbage trips when you could be paid the same rate with Better seniority?