okay I called and they say it's not possible to book into B on a PE fare. Also this is a TA ticket so no FFC if less valued.

I tried to use the change flight option on united.com and observed a few things:

- I'm able to see the lowest K fare to reprice for even exchange (even before outbound is flown)
- I can request up to V fare without add collect on the non-stop or routings with connections (original routing is UA R and UA B)
- However, if I request B class, somehow I can even exchange for a non-stop in UA B, while routings with connections (or original routing) in UA B all the way are asking for $1k+ fare difference
- As R fare isn't available on any UA only routing, add collect is required ($300ish for A and $600ish for O)
- There is one routing with LX V + UA R and the fare difference is only $8