note for documented the fixing of overlapping landuse and determine if outline and building name is correct or not :

Project "Les Sources" is conducted by https://www.belgianland.be/
Initial permit : https://openpermits.brussels/fr/_07/PFD/629625 include the all perimeter. 
The permit generate "town planning charge" and made the aquisition by SLRB/BGHM of this building https://www.openstreetmap.org/way/967236084 : https://slrb-bghm.brussels/fr/communiques-presse/130-logements-sociaux-de-3-projets-cle-sur-porte-acquis-par-la-slrb

After reception phases the building is operated by the SISP/OVM's (emphyteusis or transfert to the patrimony)

So for this social building "Life Style" i only find one reference : https://www.lessources-brussels.be/fr in the galery ; between garden et aerial ... https://comensia.be/index.php/a-propos/notre-patrimoine/ (fourth picture) name this "Les sources" and i don't find any indication another name. 

For the south outline ; this part is still on instruction : https://openpermits.brussels/fr/_07/PU/1697761 and it's a greenfield today. 