Thanks for this useful plugin, but there's one feature it should have.
If I have structure like this:
- Grand Parent 1
-- Parent 1.1
-- Parent 1.2
--- Child 1.2.1
--- Child 1.2.2
-- Parent 1.3
--- Child 1.3.1
--- Child 1.3.2
--- Child 1.3.3
- Grand Parent 2
And if LOOP = 'expand' then
1) next_page_not_post on page 'Child 1.2.2' gives link to 'Parent 1.3' which is fine.
2) next_page_not_post on page 'Child 1.3.3' gives blank, but it should link to 'Grand Parent 2'.
http://wordpress.org/extend/plugins/next-page-not-next-post/