I have a similar workflow need.
I am encoding video from BetaSP, the caption data is getting encoded in my .MOV file. Going through a DVCPro deck and using just regular old HTSC DV Compression. Double checked my file and the Closed Caption data is there. The last step for me is to get file to MPEG-2 in a way that preserves that data. According to the DVD studio pro manual it appears this should be possible, but right now I have yet to figure out how.
Peter Cook
Cre8tive Group
304 E. Main Street
Wilmore, KY 40390
859-858-9054 x28
https://www.cre8tivegroup.com
https://www.petervcook.com