I need force users to register on my site with just email only. I cannot use the Email Registration module. With this module, a username is generated and assigned based on the user name part of the email address. Subsequent users who have the same name (email prefix) are numbered sequentially. For example, "johndoe@exampleA.com" would be assigned username "johndoe", "johndoe@exampleB.com" would be assigned "johndoe001" and so forth..
The use case is that I have a number of subdomains that I am using Bakery on and need to ensure that there aren't any conflicting slave site accounts. The Email registration module will just create a tokenized username with appended unique IDs, creating conflicting accounts.
I figure by forcing email addresses, I can bypass most of this as an issue. How can I completely eliminate the username field and just use email field?