R. Kelly's Alleged Sex Slave Victims' Families Involved in Lifetime Documentary

Lifetime's diving deep into R. Kelly's alleged sex cult with a documentary series ... and TMZ's learned the network's getting tons of help from the families directly affected.

Tim Savage -- the father of alleged brainwashed sex slave Joycelyn Savage -- tells TMZ ... 3 families are directly involved with helping Lifetime produce the documentary. Along with the Savages, Tim tells us Michelle Gardner's playing ball, as is Angelo Clary.

And get this ... one of the scenes features Michelle in L.A. looking for her daughter, Dominique. Michelle tells us she recognized her daughter in a video we posted earlier this month interviewing Joycelyn. Dominique's the one wearing the baseball hat and black t-shirt.

We're told Michelle somehow found Dominique and brought her back home with her. As far as Angelo ... he's been trying to find his daughter, Azriel, for some time now. As we reported ... Angelo claims Azriel met Kelly when she was 17 and shortly after meeting Angelo says she moved in with him.