You'll probably have to update one of the attribute values under `ou=configuration,o=gluu`.
You can use "Cache Refresh" to sync the user information across multiple LDAP servers. See [https://gluu.org/docs/gluu-server/4.2/user-management/ldap-sync/](https://gluu.org/docs/gluu-server/4.2/user-management/ldap-sync/)
If you can't sync the `userPassword` attribute, you could authenticate against multiple LDAP servers with a person authentication interception script. See the `basic.multi_auth_conf` in [https://github.com/GluuFederation/oxAuth/tree/master/Server/integrations](https://github.com/GluuFederation/oxAuth/tree/master/Server/integrations)