I believe that nobody who is alive today has any more knowledge than what we know. So no wonder nobody from either side is really talking. The Arnold side was a little more open but also had no actual knowledge of JAZ. Not a surprise.
All we know is that the whole circumstances were difficult back then. Summing up:
MA left school, got pregnant by a guy we do not know. Noone knows what happened to that child, it is suspected to have been given away. Within 2 years, she was pregnant out of wedlock again, this time by AZ. When this baby, JAZ, was 2 or 3, MA worked in a cinema as cashier. Got pregnant again by the manager who was married to another woman. MA lived in some sort of low income skid row type building, JAZ died around the time his half sister was born.
I wonder if there are census records showing where he lived at this time.