key part:

"[A lawyer specializing in this sort of law] explained that when dad and Chrysalis came to a handshake agreement, as long as the paintings were originally considered “works made for hire,” the copyright for the paintings always belonged to Chrysalis, thanks to the 1909 Copyright Act. Copyright laws were amended in 1978, making it more difficult for commissioned works to qualify as “works made for hire,” especially in instances where a contract was less-than-specific. Unfortunately, the courts have heavily favored publishers for cases that dated prior to 1978, which means dad missed the cutoff by a scant seven years."