If the child is over age 18, then the parent is not responsible for the child's medical bills. The child is legally responsible for anything that the insurance policy did not pay.
If the step-child is in college, you are still responsible for paying their medical bills. If they aren't a full time student, you may need to check with your insurance plan because most insurances will not cover a child over 18 unless they are full time students.
Where you can purchase medical insurance for a child depends on where you are located. For example, You can purchase medical insurance for a child from providers such as CHPlus and Family Health Plus in New York.
As long as your child is in college full time, most insurances will cover your son until he is 25. You should ask your specific insurance policy about their rules and guidelines.
Legally, no.
Not unless they are still listed on the insurance policy. Under the new laws in the US, they can be on the policy until they turn 26.
If your child is covered under your insurance while in college, the coverage probably ends in the month that the child graduates. You can probably purchase Cobra coverage at a higher rate until the child buys his or her own coverage. You should check with your insurance agent (or the actual policy if you have it) to be sure of the ending date of your graduate's coverage.
Legally, as long as the child is 18, there are no obligations.
That is dependent on the court orders. see link
If you live in a state where an 18 year old is a legal adult then that adult is legally responsible for himself or herself. He or she is responsible for his own debts and liabilities. You are not liable for co-pays on his medical bills. If you are covering your adult child on your health insurance you are responsible to pay the premiums. If you choose not to cover your adult child on your health insurance plan you are not required to keep him or her covered under your plan. He or she is responsible to obtain their own health insurance plan if you choose not to put him on your plan. Most insurance plans will not place an adult child on your insurance plan if he or she is not attending school....and there can be restrictions on the amount of classes a student is taking to qualify to stay on your health insurance plan. Any adult child living in your home you are not legally responsible to provide health insurance, pay his or her bills or medical bills. You are even legally allowed to charge that adult child for expenses incurred by him or her.
Call your insurance company and ask them for the forms you need or what the procedure is to add a child to your coverage.
If she is still a minor and not emancipated then Yes, The Legal Guardian can still be held financially liable for the child's actions.