The issues to consider are immigration, education admission requirements, fees, academic performance (school and student), and social issues. All of these contribute towards some future life plans that the OP has not elaborated. That life plan may include the current family of OP, wife-to-be, and children (currently 13 and 16) remaining as a family unit, for 5 years or perhaps for 10 or more years while undertaking higher education.
Teenage years are a time when peers start to become more important than parents. In my experience, this is universal. A child who is moved between countries before their teen years will likely easily make new friends. During teen years this becomes more problematic, and even more when moved to a different cultural and language setting.
In summary: consider the social issues very carefully as I think these will be the dominant matters, and discuss your planning and all the options with these teenagers before you decide anything. The outcome of your plans for their lives will be determined by the children, not necessarily through overt actions.