I've got a Google id, but also a MyOpenID.
All my Stack Exchange accounts were created via the Google account id.
How can I setup Stack Exchange so that I can also login with MyOpenId; in order to be able to choose either Google or my openid?
Head over to your profile page.
Once there, click on My Logins & click on Add more logins to add your MyOpenID account
Go to your profile page, click on
At the bottom of the popup there is a link to