I assume I can use rewriteCond and {QUERY_STRING}, plus the technique VS suggested to capture the params, but I'm not sure if I apply the RewriteCond whether that will prevent the Redirect executing if the condition isn't matched? In this case I'm not worried if there's a match, just if there is to add the params on.
Yah it would prevent the RewriteRule from redirecting if there were no matches.
One workaround would be to have an additional RewriteRule with no RewriteCond.
RewriteCond blah blah
RewriteRule blah yadda
#if match do above
#if no matches...
RewriteRule blah blah
Bompa