Due to weather in the Northeast today I’ve had more flight cancellations and spoken to more DM agents in 1 day than ever before. I had a ticket where I purchased a FCM fare and was told several times these “upsells” were non-transferable. I pushed back telling them I wasn’t voluntarily changing my flights and was trying to rebook due to my original flights being cancelled.

What is is the actual rule here. Are these treated like any G/A/P/F fares in terms of being able to SDC into another premium cabin seat or is there another rule that governs these. I’ve tried searching for answers and couldn’t find anything. Appreciate any help.