@Robert ******
Harsh, but I complied with your rule. I just wanted to show the information about it. It's called a Guardian visa but yeah it's actually just an extension one can get as it states that a Non o is required to get this kind of extension which was my enquirey:
"Along with the student visa of the child, the initial visa can be extended into a Guardian visa 21 days before its expiration and once all the requirements have been met. This is done at the Thai Immigration office."
The applicant has to be established the following:
Birth certificate of the child as a proof of relationship to the child.
Admission Letter and Enrollment Form as proof of the child’s enrolment in a school in Thailand
Deposit of THB 500,000 in a Thai bank account so you would have to set up your Thai bank account.
So all I'd need to get this kind of extension is a birth certificate to show my relationship and a letter from her school. It doesn't say anything about family courts and legalisation of parent responsibility...