Update: I seem to have gotten it working, by inserting the following code directly to function bb_safe_redirect within functions.bb-pluggable.php, right before the line checking against $allowed_hosts:
$allowed_redirects = array();
$allowed_redirects[] = 'offsite-feedback-forum.com';
$allowed_redirects[] = 'base-blog-url.com';
$allowed_redirects[] = 'base-blog-url.com/wordpress-installed-directory';
add_filter('allowed_redirect_hosts', 'add_allowed_redirect_hosts');
I originally tried to do this from a plugin, as the code above is copied from a handy WordPress plugin, but I was not able to get it to work without sticking it right within the pluggable.php file. If anybody has a better suggestion, I’d love to avoid editing the core files if possible!
