• On her computer, my wife is permanently logged into her Google account.
• She never uses (or has used) SU.
• I want to fix stuff on her computer and access my SU account to ask questions.
• I always use my Google login to login to my SU account (well, I'm also permanently logged in to Google and all SE sites I use).

How can I use my Google login to log into SU on her (Win 10) machine, without having to log her out of her Google account?

• I tried just logging in with my Google user/pass, but then I still get redirected to Google, where it says 'SU is asking for permission' to log in with her account.
• I tried several variations of using my Google OpenID login under Other login options/OpenID login, as per the answers to this question, but this gives me No OpenID endpoint found.

I would like to do this without SU/SE staff being involved. They have enough to do already ;-)