Have had great success with DVD images successfully made by SVCD2DVDMPG - use SVCD2DVDMPG to author, then ImgTool to make image. Then burn or watch off hard drive.
Anyway I made a "short DVD" recently using just one SVCD.
Don't have the original SVCD's anymore

I now have a second SVCD I want to put with this before burning

I plan to demux the "short DVD" using Smartripper
I plan to rip to mpg (combined audio and video), then use SVCD2DVDMPG to add in the second SVCD

Any problems with this?
Particularly any problems with this header issue?
Smartripper the best to demux?

Jeff