Harmy, I've begun asking around with some people I talk to at another site that do a lot of Blu-ray reauthoring (to add extra subtitles and/or audio tracks, etc.), to see what they have to say about the process. I haven't heard much about what this one guy in particular uses (though I think it is mostly Scenarist), but his main bit of advise/caution was that you should be mindful of not going past the max bitrate, which includes all video, audio and subtitle stream bitrates at any given time. So, the amount of audio tracks you want shouldn't be a problem, as long as there isn't too much data (even if just a spike) to stay within BD specs. What I take from that is maybe we can't have more than just a few lossless tracks, or we could start running into bitrate issues... I'll let you know if I hear more. Also, do you have any questions you'd like me to pass along?