Being a John Sebastian fan and being bored today, I googled "Mark Sebastian", who I know is John's younger brother and who co-wrote "Summer in the City", the Lovin' Spoonful's biggest hit. Much to my surprise, this is what I found...
http://cdbaby.com/cd/marksebastian This is totally new to me... anybody else ever hear this story? The only Sebastian story I ever heard related to Brian was that Brian had some interaction with John around the time of his '88 album, don't remember much more than that. Anyway, thought this would be of interest...