Currently, there is no central place where you could change the page delimiter. But we intend to add this feature in the next release.
For the time being, you can achieve the required behavior by adding a friendly URL in the page properties. What I mean is add an additional URL, e.g. parent_child.aspx
instead of parent/child.aspx
and set it as default URL for the page. Unfortunately, there is a bug in the Page Friendly URLs in the current version os Sitefinity
, so after adding a new URL you may not be able to delete/modify it subsequently.
Still we are suggesting that you wait for the next release where you will be able to set the page delimiter in the Web.config file.