I had a thought - since Linda's second husband is in the movie business, I wondered if her first husband Robert could be also so did some checking.
There is a Buddy Ruskin who was the writer for the Mod Squad - a show from the late 60's early 70's
I tried to find a photo of Buddy Ruskin - much harder than you would expect
and no bio on him either so no way yet to know if he is Robert
Ahh I just found a blog for Purepop - Eli Culberton - he mentions in one blog his manage Buddy Ruskin who he says was his manager and also was the created of Mod Squad ( so that matches) and he says he died in 1975/76 so that matches with death of Robert.