Please understand i'm not trying to be difficult, but i don't see how my case differs from other ones that i have read on this forum e.g. "Sims 2 CD to DVD Backup" -
http://fileforums.com/showthread.php?t=64391 and "The Sims 2 University Update" -
http://www.fileforums.com/showthread.php?t=68751. These 2 threads give advice to copy the contents of your Sims 2 CDs to your hard drive for burning to DVD, and also ways of solving the need for Sims 2 CD4 during installation of the expansion.