Welcome to the Forum.
What you are looking for is a DVD authoring software program. Unfortunately CloneDVD is not a DVD authoring software program.
For your project you will need a DVD authoring program. Suggested using TMPGEnc DVD Author (http://www.pegasys-inc.com/en/product/tda.html) to author you compilation DVD from multiple DVDs. After you use TMPGEnc DVD Author to author your compilation DVD from multiple DVDs and if it is larger than 4.7GH use CloneDVD to shrink/compress to 4.3 GH to fix on a DVDÂ±R media.
This TMPGEnc DVD Author user guide is an excellent step-by-step guide user guide that will explain how to do this www.doom9.org/mpg/tmpg-dvdauthor.htm