Add custom option to Standard Page Attributes Meta Box

I’d like to add a simple checkbox option to the exsisting standard Page Attributes Meta Box.

Is there an obvious/intended way to do that using the WordPress API, rather than registering a new metabox for my one new option?

Unfortunately not. The only way is to deregister the metabox, and then re-register it, supplying your own callback function which mimics the original metabox, but with your alterations (making sure the names of the inputs do not change).

This method is outlined in these posts:

• custom post type taxonomies UI radiobuttons not checkboxes
• Custom-Taxonomy as categories: Remove “most-used” tab?

Alternatively you can insert the options with javascript as outlined in:

• How to Add Reminders/Notes to New Post Meta Boxes