Use TSMuxer to demux all the tracks in the DE M2ts. Remove the original file from TSMuxer then load the demuxed video and remux it to a M2ts. But DON’T include any of the audio tracks, subtitle tracks etc. just video. Vegas can’t import Ac3 so you will need to convert whichever audio track you want to use to a compatible format (WAV is best for vegas). If you want stereo then fine, but if you want multitrack audio then you will need to convert the original demuxed audio file to separate wavs using something like EAC3to first. The 97 reconstruction file, well it all depends on how you converted it to mp4. But again you need to keep the audio track separate from the video track.