I've observed the similarity between "When the Sun Comes Down" and Marble Garden in my listening before, since that's one of like three songs I really dig from the Jetzons. That said, I strongly believe the similarity is merely coincidental. The Jetzons only had one public release, The "Made in America" EP, which was only available in the US and didn't feature "Hard Times" or "When the Sun Comes Down." I wonder if its possible that the non-MJ team composers were given MJ's tape to work off? Or if theses songs were played to the other composers by Brad Buxer?