I mentioned the software, Tsunami and TMPGEnc DVD Author 3, it is all irrelevant, I managed to author it.
The problem was the way the DVD was recorded, 30 mns at a time, one segment finished and then the other started, and the second didn’t appear on the timeline.
This worked: I ripped the DVD to a single VOB file with Decrypter;
Demuxed with Womble;
Imported both streams to TMPGEnc and rendered to DVD without authoring. In the previous attempt I authored the DVD and then rendered it, the second half of the DVD had no audio-no idea why.
I imported newly rendered VIDEO_TS to TMPGEnc and authored it, rendered to DVD and for some strange reason, all 54 mns were there, video and audio.