Interesting interview with VDP from last month at:
http://noisey.vice.com/blog/van-dyke-parks-has-a-lot-to-saywhich has something I hadn't read before - Van Dyke says that "three years ago" Mothers of Invention drummer Jimmy Carl Black (who died almost five years ago) called him up and asked if he'd join yet another lineup of the Grandmothers.
Which is rather a surprise - Van Dyke was in the Mothers only for a short time in '65, and he isn't even mentioned in most of the books about Zappa and the band. Still, it would have been interesting to see him onstage with Jimmy and some of the other exes.