Come to think of it kabayan family visit visa is valid for one month and can be extend up to maximum 5 months as u told you want to enroll your children here in doha and probably you want to change family visit visa to residence visa right? but its to risky kabayan i think it is better to apply directly for a family residence instead of family visit visa to make sure that they can stay here for the whole school year, make a step one at a time kabayan, hope it helps. goodluck