Forms OID user location

When Forms11g has SSO configured with OAM and OID, by default all the users are under cn=users,dc....

Can I create sub orgs and place users under those, or do they have to be directly under cn=users?

I want to create a structure like this:

ou=sydney,cn=users,dc...

ou=perth,cn=users,dc...

I know OAM won't have a problem finding the users and do the SSO, but once that's done and it redirects back to Forms, will Forms be able to handle the user if the user is not directly under cn=users since OAM just adds the userid into the OAM_REMOTE_USER header. Does Forms perform a base search on cn=users only, or can it do a sub search from a parent org?