Create child page (subpage) with just a link

I want to add users some easy way to create subpage of a page, so reverse the select parent page. I want it to do so that it would simply preselect the parent page to the given ID.

I see in the post.php, that i should give to the $_POST of the page the parent_id parameter, what is easy, but the problem is, that the $_POST parameters are called only when you are doing update, not for creating new page.

Does anyone know some easy hack how to solve it?

thx