Sometimes the dynamic reaccom tool gives options in F when booked in Y. Does choosing this option change the underlying booking code of your ticket?
The other week my 10:10am LAX-SFO flight in Y was cancelled the day beforehand and I was given several other Y options, along with an option for the 11pm in J. I chose the 11pm in J and was instantly able to SDFC to the 8am and get the last open seat onboard. I wouldn't have expected SDFC to work if my ticket wasn't changed to J, D, R, or I -- so am curious what happens with the dynamic reaccom tool internally and how it affects the underlying ticket.