ASBLs are subject to anti-money laundering regulations just as companies. This means we need to keep an Ultimate Beneficial Owners Registry (registre UBO). Subject to the same regulations (Know Your Customer, abbreviated KYC), banks like Triodos demand copies.
UBOs or companies are its shareholders. The case of not-for-profits like ASBLs is a bit more murky, but it seems to mean “board members and representatives in general”. See: https://www.monasbl.be/nouvelles/droit/voici-comment-remplir-et-confirmer-les-donnees-du-registre-ubo.
The UBO registry for Belgium is a part of MyMinFin. Board members can access online it via their ID cards and card readers. Today, I updated our UBO registry, downloaded it, and used to answer a questionnaire that Triodos demanded of us. A copy is stored in this folder.
No action is needed for now. As we change our board, the UBO registry will need to be updated.