Adding email addresses on refer.php??

I'm trying to make more email address spaces available so that when someone is referring friends they can add 5-10 friends instead of only being able to add 3. I tried just copying the friend 2 and friend 3 lines, and making them friend4 and friend5 but that did not work. Any ideas on how I can do this?

PHP Code:

<?php
error_reporting(7);

require('./global.php');

    if (!isset($action)) {
        $action = 'compose';
    } else {
        $action = 'send';
    }

// check to see if they're logged in
if ($bbuserinfo[userid]) {
    if ($action == 'compose') {
        //default email title
        $defaulttitle = "Come check out the $bbtitle forums!";
        //default email message
        $defaultmessage = "Hey,\n\nI would like to introduce you to a great community that I enjoy and think you would enjoy too. It's a fun place with great members and a lot of activity. If you want to get rid of your boredom, or just need a place to hang out on the net, please come join me at the $bbtitle forums.\n\nTo check it out, click here (or copy and paste the url in your web browser): $bburl/index.php?s=&referrerid=$bbuserinfo[userid]\n\nThanks, and I hope to see you soon. :)\n\n-$bbuserinfo[username]";

        // load up main referral page
        eval("dooutput(\"".gettemplate('refer')."\");");
    }

    if ($action == 'send') {
        // build mailing list
        $to = $friend1;
        if ($friend2 != "") {
            $to .= ",".$friend2;
        }
        if ($friend3 != "") {
            $to .= ",".$friend3;
        }

        // check that required fields are not blank
        if ($friend1 == "" or $name == "" or $message == "") {
            // if a field is blank, get error
            eval("dooutput(\"".gettemplate('refer_error')."\");");
        } else {
            // if error free, then send mail
            mail($to,$title,$message,"From: $bbuserinfo[email] ($name)");
            // give thank you/sent message
            eval("dooutput(\"".gettemplate('refer_sent')."\");");
        }
    }
} else {
    // if guest/not logged in, show error
    eval("dooutput(\"".gettemplate('refer_error')."\");");
}
?>