I am flying SEA-LAX-NRT-SIN next week. SEA-LAX looks like it's pretty overbooked right now as it's completely zeroed out in all classes. Right now, I am upgraded on SEA-LAX-NRT using SWU.

If they are looking for volunteers and I take a bump, it looks like I have couple of options.

The SEA-LAX flight that I am booked on leaves at 7:25a. There's a SEA-SFO leaving at 7:35a [F4C4..]connecting to UA 837 SFO-NRT [F2C7D1]. There's also the SEA-NRT direct flight leaving at 12:35p [F2C0].

Will the agent book me on the SEA-SFO-NRT flight and still let me keep my upgrade using SWU or are they just not going to take anyone with a connection or just rebook me and stuck me in Y and put me on the waitlist for the upgrade?

Never taken a bump before so just trying to find out how it works.

Thanks