I think you have two options
- just change your code to show the user defined headers on the built-in
first header and show the "standard" header on a optional created header, or
- do not use the built-in header at all. You cannot delete it but you
can hide it. Then use optional created headers for both user defined
headers and standard headers.
Headers are shown in order created and I don't think order can be
changed. Since the built-in header is created first it will be always be
the topmost. The best you can do I think is hide it.
/Ashok