Firefox account: secondary email address already in use, not appearing anywhere
I wanted to add one of my email address, let's call it A, as a secondary address for my firefox account, B. However, it tells me that the address has already been verified by another user.
I checked, I did have another firefox account (since gmail, accepts "." in the name, I created by accident two accounts...B&C), but address A is not visible in either B or C.
If I try to connect with A, I don't have password which match. If I ask to reset the password, it asks for the primary address...which is not B or C! At that point I'm running out of email address that could have been used ^^ There is no address D.
I have deleted the account C just to be sure.
How can I identify where address A has been used? How to use address A as a primary/secundary address ?