(9) 1/2 Concert DVD compiled to several DVD

Had a concert season with 9 shows I need to compile to a few DVD. No problem making a single copy of each show using Pinnacle InstanstantCD DVD.
Need to compile as many .99 gig shows to a DVD (for underwriters) as i can cram on a dvd.
Running XP, guess I need an authoring program.
What is least expensive but stable software recommended?
As guessed each DVD has same file names ie VTS_Vob and Bup. I also have a PDI version of each concert (Disk Image) that InstantCD DVD will make exact copies of each individual concert, but will only alow a single show pwe DVD.

Would appreciate any help and direction