Invite-only - Allow signup from invited but no one else (part 2)

Hello there,
This post is directly linked to the previous one.

As @konrad.sopala explained to us, we have implemented this solution:

  1. Create a database connection.
  2. Enable it for each organization as needed.
  3. Use Organization Membership Invitation , assigning role & user metadata as needed
  4. Don’t use that database connection for other applications if you don’t want anyone to be able to signup

There is a big problem with this solution, and I don’t know how to solve it, so I am here to ask for your help.

The users that are created on this new database for invitation only are unable to connect to our Application.
The app is correctly setup with the two databases.
We have the first one that is linked to our MongoDB auth to use the smooth migration of our users into Auth0. This database doesn’t allow signups, because we do not want users to be able to achieve an inscription through the login interface.
Then we have the second database that is “user-invitation” and used to send invitation to new users.

When new users clic on the link in the invitation mail, everything works fine. They can create a new user on Auth0, they are redirected to the App and be logged in.
But there is a (big) problem, when they go to our app later. Our app redirect to the login page (without mentioning any specific connection, as we do not know if the user is on our first database or the second).
The user is unable to connect as Auth0 tries automatically to connect the user to the first database (which don’t have the user).

How can we do ?