I knew her brother-in-law, Darby Slick, for many years. He introduced her to his brother, John, giving her that last name.
Darby wrote "Don't You Want Somebody to Love" - really ! - and was in The Great Society with them both prior to the Airplane.
I knew him because we both had deaf sons who went to school together. One time our kids were going to the same deaf summer camp,
and we had to drop them off at a meeting spot in the central valley. A whole crowd was jammed in the swimming pool, and I asked Darby a favor: I wanted to ask my son - actually my late wife's son - if I could ask his mom to marry me while he was away at camp.
I was pretty bad at sign language at the time and Darby interpreted for me. Here I thought we were having a real private talk, but the whole pool-full exploded in cheers because they could "see" the conversation !   Grace was actually a neighbor in Mill Valley later in that long-ago life.    A utility worker was clearing brush on the wild land next to her house and set it on fire. It survived but she moved along.    Riggy