Parents can choose the school children will go to but they have no right to have a space on a certain school . In Belgium, education is compulsory from age 6 to 18. However, this does not mean that children have to attend school but that they have to receive some sort of education (home-schooling, technical education, etc ). Schools may have different requirements (due date for application, proximity, grades, parent was a former student of the school etc) regarding your child’s enrollment in the school, so the decision belongs to them. The only possibility to appeal the school decision is if it was based on discrimination grounds.
If your child is eligible for enrollment (age, has finished primary education) a secondary school can’t refuse enrollment without a justification.
A secondary school can deny enrollment in 4 special circumstances:
In Flanders, if your child was denied enrollment because of one of the above reasons than the school has 4 days to send you a written notification with motivation of the refusal.
For more information:
https://onderwijs.vlaanderen.be/nl/problemen-bij-het-inschrijven#weigert
http://www.agodi.be/commissie-inzake-leerlingenrechten-een-klacht-indienen