Interestingly (but sorta pointing away from the O.T.O.), And in "Sex and Rockets ; The Occult World of Jack Parsons" (a great little biography ) by John Carter, Heinlein's friendship with Jack Parsons, the head of the OTO branch, Agape Lodge, is mentioned. With the amount of science fiction authors in and around the OTO at the time (notably L. Ron Hubbard) this is not surprising.So Leslyn Heinlein might have been involved as well.