[keycloak-user] Keycloak Multi Tenancy implementation with login through javascript (a webpage)

Hello all, I want to assign different realms to different clients (organisations) in keycloak. The login to keycloak is achieved through a webpage which acquires a valid token from keycloak which is then passed with the rest requests that I make from my website to a springboot server that uses a keycloak adapter for authentication. Now, the javascript adapter needs a keycloak configuration file that has details about the realm that I want to log in to. But, the problem is that I do not know which realm the user belongs to because he / she can be from any organisation ie. the login page for all organisations is the same. What is the best way to achieve this ? I assume that this kind of approach is quite common these days but cannot find a solution.. Regards, Vikram