Splice aMember user onto vBulletin

The sticky thread at the top says that with BB registrations, as long as the User Name, Password and Email match that it will tie a new aMember account to the existing BB account.

However, with vBulletin I'm getting an error in the aMember signup that the account already exists.

So is there a way to manually splice an aMember account onto a vBulletin account?

The only thing I can think of is to create a new account in aMember, delete the account in the vBulletin backend, put the aMember ID into the appropriate column in the vBulletin database and.......

That's where it falls apart for me... that seems too simple.

Thanks!