It doesn’t matter who is to “blame” here. The daughter is not competent to contract and so no valid contract was formed. Period. The dealer can come collect his car and return any money that was paid.
“The dealer can come collect his car and return any money that was paid.”
No one purchased a car and there was no financial transaction.
This is just a story about a Texas mother leaving her Downs Syndrome child unattended for an extended amount of time, and outing herself as being less competant than her daughter.