Age of majority and disability

[ACDCKING]

What is the name of your state (only U.S. law)? MO
My son will be 18 in January. I have custody of one son, age 16 and mother has custody of son who will be 18. The son who will be 18 in January has autism but is a straight A student and is already accepted into a program following high school or that will train him as a criminal lab tech. Mother made a comment that once he is 18 she is going to get him on disability. Is this possible? He has some speech impediment but other than that is very smart and has awesome grades.
Also, there is no child support order since we each have physical custody of one, after 18 would she be able to ask the court for child support ongoing due to his autism?

 

[Banned_Princess]

if he is going to get disability (which if he was disabled enough he would have already been collection) then why would you be asked to participate in his support.

didn't the judge know about his disability at the time of divorce, and the child support of none decision?