Are both blackberries on the same carrier?
If they are, there is only 1 BIS account, and only 1 BB can be registered with it at any one time.
If they are on different carriers, he has 2 BIS accounts, and can setup the email address in both BIS accounts.
"That's it then. Cancel the kitchen scraps for lepers and orphans, no more merciful beheadings... and call off Christmas."