The solution is quite easy, if you don't mind not having menus or subtitles.
Rip the disk to your HDD, and run the main .m2ts through the freewaer tool TSremux, keeping the audio track(s) you want. Choose Blu-ray output, and PDVD will play the resulting stream fine.
As I say, you'll have no menu and any subs streams you keep won't ben seen by PDVD.
Is there a similar solution for hd-dvds? Something that would join the two main feature evo files together, and let you pick which audio track to use and output the finished file as an HD-DVD, so I could still play it in PDVD Ultra similar to the TSremux program.