I used to below to the two other forums that I think this replaces, but my old usernames don’t seem to exist.
I haven’t been here for a while. Would my old identities have been deleted?
Yes
You have to start over
welcome here, the official openSUSE forums
Don’t worry, it’s same for all user 
Due to technical problems (actually darn good security in forum software) users from other forums have not been imported into the openSUSE forums. Users with an openSUSE login account can use it to login to the forums. Users without an openSUSE login account will have to create a new account before they can use all the features the forums offer. If the user ID you want is already taken, you will have to select another user ID.