I have been running whmcs as a parallel service for simple soclal/crm i had built around ci 1.0 and smarty themes some several years ago.
I just updated our whmcs instance to 7.n and want to merge and sso or open id our existing user table so that my club members can get register or transfer domains mapped for their social slug.
my only requirements are that we do this in screen share together so that i can rapidly answer and direct questions so we get this implemented in a days work, or less. In my apps table we hold my members whmcs user id. Their emails don't necessarily match. Follow on work available of course.