I have main Q&A site and i have done many Q&A sites ...user wants to login through my main site or sub domain site..
It is possible ...
My site http://asktoweb.com/ is main website.i have many sub sites are like http://boardgames.asktoweb.com/,http://anime.asktoweb.com/ more like..
Check this may any of this helps you.
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.