This is working fine. However, for forms such as contact.html I want to be able to dynamically return success and error child pages (I am presently returning the same form, which doesn't help analytics).
The above works if I hardcode contact.html (the parent of the success and error pages) but I'd ideally like the htaccess file to be flexible so as to automatically use the parent page such as contact.html so as to work for all forms anywhere within the website.