Visas for minors

I have children who are minors.
They are staying in Romania using family visa. Family visa for them is valid until they become 18 years old. 
After then, I am hoping that they will get students visas. But  when they become 18 years old, they might still be high school students. because they are studying at Romanian  language school for foreigners right now.
After they finish the course, they are going to enroll in  Romanian public or private school. It means they one year behind other students of their age.

I have few questions:

1. Could they get an extension for the family visa because of that?
2. Is it possible that they can get a student visa even though they are attending high school still?
3. What kind of visa  can people who are between 18 and 20 years old get?

Do you by any chance know about other kinds of visas for minors?

Here's some answers to your questions, though you may want to consult a immigration attorney and explain your entire situation and goals.

1. Possibly, you should ask a legal professional, or IGI.
2. I think not
3. There are no special visas for 18-20 year olds.  They can apply for whichever visa suits their purpose of stay in Romania, be it studying at university, working, volunteering, etc. 
4. Thereare no other kinds of visas for minors, as they are not legally responsible for themselves and are dependent on parent/guardians.

If your kids are unmarried, you may be able to continue to sponsor them on a family reintegration visa.

Thank you for the reply. It was very useful for me. I have never heard the information.I am really glad. I hope that I can continue to sponsor my daughters on a family reintegration visa.