Littlefamily, if you want a good chance of getting into a small(er) school at primaire level, choose a house in Wezembeek-Oppem or Kraainem rather than WSP as then you can choose la Fermette, Diabolo, St Georges or Notre Dame de la Trinité, the latter 2 I have been told have around 200 children in them, they are not oversubscribed simply because only those children living in Wezembeek and Kraainem are allowed to attend them. But the only word of warning is that if you move out of these "facility" communes, your children must leave the francophone schools. La Fermette has masses of anglophones in the school, concentrated in the lower years, you might see that as a positive or a negative. Parts of Wezembeek and Kraainem are classed as Stockel, which consists also of the area of WSP around Place Dumon, some housing in these "facility" communes are just minutes from the metro and shops and cinema centered around Place Dumon, it's not the prettiest of Brussels squares but has great facilities. Tram 39 runs through Wezembeek too.
Only hearsay from a few families I know with children at Dames de Marie, heavily oversubscribed, small and friendly, good academic standard but not up quite with St Michel or Mater Dei, also does Dutch immersion. I went to their open meeting last year and this ended up as 3rd choice on our child's list. It helps to be under 4km from the school and at your nearest primaire (of same type) in order to pick up enough points to get in - a boy in our child's class is just over 4km (not so good thing) and was at 2nd nearest Catholic school to his house (a good thing) and yet he did NOT get a place at this his first choice school chosen because his elder brother is at St Michel, he struggles a bit at school and his parents wanted a smaller school in the direction of his brother, this boy finally got a place at another similar sized school at the end of August.
Crommelynck, well I only know one child there, not by choice but because in the 2009 lottery he failed to get a place at Mater Dei or Don Bosco, his 2 nearest secondaries and was only offered Crommelynck or Eddy Mercxx. I'm sure it's not a bad school, but you just need to spend 10 minutes in the morning outside the school to discover a very hig proportion of the children there come from outside the commune - don't even think of taking the 39 tram between 8am and 830am from Stockel and Montgomery metor stations in the direction of the school, UNLESS you like being a squashed sardine. When I asked our head teacher for her views on the school, she rolled her eyes and then said it would be better to look elsewhere as our child needed a bit of stimulation. But I certainly don't get the impression it's a dumping ground sort of school, and compared to the children I've met hanging around AR Woluwe St Lambert, the next nearest AR school, and being completely subjective about their behaviour and backgrounds, AR Crommelynck seems better.