Login Redirect on Multi-site?

This is a great plugin and I’m using it on a multi-site setup.

I’ve added a login redirect by inserting the following in the theme’s functions.php file and it’s worked fine but how would I do this so that the redirect URL is different depending on the site the user is logging in from?

/*---------------------------------------------------*/
/*This is the redirect after login*/
/*---------------------------------------------------*/
add_filter('wpml_redirect_to','my_wpml_redirect');
function my_wpml_redirect(){
return 'http://xxxxxxxx.net/xxxxxxxx/welcome/';
}
/*---------------------------------------------------*/

I’m not that familiar with PHP and any help is appreciated.

Thanks,
Mike

http://wordpress.org/plugins/wp-modal-login/