Keycloak: How to override Welcome Screen redirect behavior (to custom realm, instead of master realn/admin)

Question

I am using Keycloak (24.0.2) as a standalone self-registration app (with some custom fields) for a small non-profit organization. Keycloak runs as docker behind nginx and is served under keycloak.myorganization.com. I have two realms: master (the default one) and members (where members will login/register).

Now, I would like to have users automatically forwarded to the "members" login/registration upon entering the base path. I set Frontend URL for the master realm to keycloak.myorganization.com and to members.myorganization.com for the members realm.

I also modified the docker environment variables:

KC_HOSTNAME=members.myorganization.com
KC_HOSTNAME_ADMIN=keycloak.myorganization.com

Nginx does the SSL termination and uses proxy_pass to forward everything to localhost/docker for both members.myorganization.com and keycloak.myorganization.com.

However, when I open https://members.myorganization.com, I get forwarded to the admin/root console, not the members realm login, which is available under https://members.myorganization.com/realms/members/account/.

How can I directly forward https://members.myorganization.com to https://members.myorganization.com/realms/members/account/ ?

In the Migration Guide, it says:

If the Admin Console is enabled, the welcome page will automatically redirect to it if the administrative user already exists. This behavior can be modified by setting the redirectToAdmin in your theme.properties file. By default, the property is set to false, unless you are extending the built-in theme, in which case, the property is set to true.

Does this mean I will have to create/override the theme to modify the redirect behavior?