I haven't seen him in a while, probably since my sister's wedding maybe a decade ago. His daughter was at my cousins wedding just a few months back. They are all lovely folks.
David ran a cattle ranch in Northern California for many years, and we would visit and go fishing on the property when I was growing up. He taught my sister how to drive manual stick shift and taught me how to properly BBQ. I never got much music instruction from him, but my grandmother played cello and piano and had some guidance for me.
His wife, JoRita - probably had the best sense of humor but was a tough country kind of gal. They were incredibly kind and generous to us growing up - but not fancy. They preferred spending time out on the land in an RV, moving cattle, riding horses and off road vehicles. Eating simple and fixing everything themselves, despite owning houses in San Diego and up in the Puget sound area.
Last time I spoke with David he had mentioned that he was the actual bassist on the Monster Mash - as he was conveniently in the studio at the time of the recording and they needed an extra player. It's not something he wanted to advertise much, and I don't recall who is credited on the track.
As far as writing "If" - I wouldn't take David as a song poacher, he has enough talent as it is. It's probably a hard thing to prove. My grandmother had the charts framed at her house in the Bay Area since she was credited for the string arrangements. I think they were pretty proud of that one.
The boy band N'Sync asked David to write their second album, and he turned them down.
He's mostly been involved with country music the past few decades. Not sure how musically active he is anymore, but he seemed in good health and happy to catch up when I saw him last.