You need to check with the international school if they'll allow your child to attend on a dtv. Some will and some may ask you to have an education visa. Next, the parent applies for the dtv (whichever category) and then apply for the kids as dependants. I did soft power before applying for my children. It takes some time as the main applicant needs to be approved first before applying for dependants, so make sure you're in a country where you can stay a few weeks