Hi @roy.e,
Welcome to the Auth0 Community!
Yes, this is a valid approach for managing multiple merchants within Auth0 by leveraging the Organizations feature. Our Multiple Organization Architecture documentation explains this very well.
Unfortunately, you can only query up to 1000 organizations that belong to a user by passing in the page and per_page query parameters in your request.
For example, here is what the request would look like for the first 100 organizations for a specific user:
GET https://YOUR_AUTH0_DOMAIN/api/v2/users/{user_id}/organizations?page=0&per_page=100
And here is what it would look like for the next 100 organizations for that same user:
GET https://YOUR_AUTH0_DOMAIN/api/v2/users/{user_id}/organizations?page=1&per_page=100
References:
Let me know if you have any questions.
Thanks,
Rueben