In each country, a unique national organization (an association or foundation) is responsible for the project and it's implementation.
These national organizations decide through their governing bodies which actions to carry out under the project's banner.
An international association with representatives from the four national organizations, meets regularly. It is responsible for the overall long term orientation of the project, and keeps the project coherent throughout the four countries.
The international association is a place for exchanging and brainstorming (but not technically for decision-making). Suggestions can only be considered as approved once the four national organizations have validated them.