if he's in Nascar. theoretically he could drive in the big ones.
If his other relatives all start with 'B' then that lets out the Labonte explanantion (obviously) and if his name's Brad and his brother's name is Brian then they'd have to use 'BRA' or 'BRD' and 'BRI' for Brad and Brian. If you have to use 'BRD' you might as well just use 'Brad'.
my $.03 Cdn lol.