The story reported in press accounts is that Desiree had kidney failure, and signed over custody to Kaine when she left the USA for medical treatment in Canada.
I have NO idea if press accounts are true & accurate.
Terri Moulton Horman had told her mom that she was a close friend of Desiree's and it was at this time that she moved into Kaine's house with her son James, in order to care for Kyron.
Desiree has recently stated, however, that she was NO friend of Terri's and never spoke to her at any time before Kyron was a year & a half old.