Who Provides Coverage for the Child?

My son is enrolled in his father’s wife’s health insurance by court order. We receive child support until he is 18 years old or graduates from high school. The latter applies. When the child support ends and there is no further court order regarding health care, the does the coverage end, if so, what is the process to obtain health insurance for my son. My coverage is through employer disability and does not offer coverage to any family member.