(Sound\s*\{\s*Name\s=\s$Sound;\s*Priority\s=\s)([\d\D]*?);
(Sound\s*\{(\s*)Name\s=\s$Sound;\s*$)

##</code><code>##

$1$Pri;
$1$2Priority\ =\ $Pri;\n

##</code><code>##

s/(Sound\s*\{\s*Name\s=\s$Sound).*?;/$1; Priority = $Pri;/m