Sub wiki Login URL issues

I plan to use main wiki and a set of sub wikis. Idea is to use this as our extranet. So I give one URL to different clients but they have separate sub wikis.

Main wiki authentication works fine. When I create a user in sub wiki level I need to use sub wiki URL to login and that also works. If I use main wiki URL it given to login to sub wiki I get authentication invalid message. Now with this way I need to tell different clients to use seperate URLs for their sub wiki, my need is all of themto give main wiki URL and with login credentials they get logged into their correct Wiki. I tested this and it worked with earlier version but new 11.1 this is not working
Can somebody helpPreformatted text