Originally Posted by ThreeJulietTango

Even if you used Same-Day Flight Change to change to a higher fare class on a different flight, you would still earn EQPs based on the original fare class purchased. You cannot SDFC into a higher coach inventory on the same flight.

Generally, SDFC books into the same inventory or the lowest available coach fare if the original inventory is unavailable.

If boosting your EQP earning is your goal, you should have the ticket reissued, which would be subject to the $200.00 change fee and fare difference. On some fares, the change fee is waived if you rebook into a higher cabin, so that might be an option to explore as well.