Getting my six-grader into a public school (Brussels)

Hi!

I should move to Brussels in a few months, with my two kids, aged 11 and 9. They are both educated in the French system, and now I want to get them into a public school in Brussels. Now, my daughter Protected content in the French version of the 6th grade. From what I understood, next year she should be going to the secondary school, after having passed this CEB (or whatever) test. How can I, if I can at all, get her into the 6th grade in Brussels and have her pass the test in time for enrollment into the secondary? Is it possible at all??? I might have them join me only in September, though I would really like to avoid that. However, if that's recommended, is it possible to get her into a decent secondary school without having gone into a primary school in Brussels?

Thanks a lot!!!