For a given content type, if a new node is created and no book is assigned, I'd like to create a new book and assign the new node to that book.
(some background - that content type is the book cover, and for editors to create a new book I ask them to create a cover first. this makes more sense for them. The 'add child page' links will then appear automatically. I know they can select 'new book' on the create page, but that makes no sense in that context - alternatively, if I could have that selected by default, that would work )