This is not accurate in any way. Once you begin a trip, any changes that are made are subject to the same Daily Reassignment Pay as line holders EXCEPT that it only applies at the first point of change, and only to the day that you're currently on.

Example: you are on a three day block of reserve. You are assigned a turn, DAL-BWI-DAL. When you land in BWI, scheduling calls you and says after getting to DAL you're now going to MAF for a sweet seafood buffet overnight, returning to DAL in the morning. You would get DRP on the DAL-MAF leg (premium), while only normal rigs apply on the leg back in the morning. You land in MAF, and scheduling says they have another change for you. Instead of just flying back to DAL, you report at the same time and are flying MAF-LAS-STL-BWI for an overnight. You don't get move up pay, BUT if the MAF-LAS lands after the original DAL leg was supposed to land, it falls outside of the new "original" pairing that you were assigned the night before, so it trips the MAF-LAS leg to DRP, along with all subsequent legs on that day. The following day is at normal rigs and pay. If the MAF-LAS leg doesn't fall outside of the "original" pairing, then that leg is still at straight time while the subsequent legs are paid at premium.

This is why many people, including relatively senior people like me, bid reserve on purpose. During times of operational crisis, it can be quite lucrative. A lot of the time on reserve you are assigned pretty much day by day because you're covering broken trips. As they keep resigning you new bits of broken trips, those legs added are generally at premium. And as a reserve, you're almost always the first person to get reassignments, probably because of some skysolver logic.

Basically, once you are on a pairing, any changes made to it fall under the same rules of a line holder, but those rules stop applying at the end of the day of the first point of change. In my example above, if you were assigned a three day with MAF and BWI overnights, and they called you after you checked in to inform you that you would be just flying directly MAF and then being moved up the subsequent days, only the FIRST move up day would pay at premium, and barring further changes, day three, though technically a move up, would not pay at DRP. That's where one misconception lies.

The other misconception is that it only applies to changes on the day in which you are currently operating, which is also not true. If I checked in for my example above, a three day, and after checking in they call me and say we changed your third day to a move up, but the first two days are still the same, I would get DRP for day three, even though it's two days away and i haven't started that day yet.

Yet another reason we need a clear re-write of the contract. The language is very convoluted,.and if you play the reserve game, either by choice or because that's all you can hold, then you have to be especially well versed in the contract, which unfortunately is usually not the definition of a junior pilot.