There was an earlier question in this thread regarding upgrades that I don't believe was answered, and which interests me.

Namely, are fares booked with Merrill+ rewards points considered as paid fare classes by the operating airline? As I tried to make a booking on the Merrill+ travel website for a one-way flight on Turkish Airlines, nowhere was I able to confirm what the actual fare class would be. How can I confirm the fare class, so that I know whether it will be eligible for an upgrade to J class using Miles and Smiles points?