RU.08 said:

You can do it with BDedit on PC. Author your disc with the "non-seamless" version, and then use BDedit to set the MPLS files as seamless.

Interesting. Just do it as playlists and then switch the seamless flags?

Edit: I'm still learning about this stuff, so sorry if this doesn't make sense -

Non-seamless files should have multiple audio tracks (one for each alternate video), right? And seamless should be multiple video angles paired to the same audio track? If so, how should it be set up in order to later change in BDedit?