Suggestions for organising pages?

I host a fiction-writing community. We use pages for the fiction, and Posts for a community blog. We have many on-going stories, and subsets of stories, and we need something that will let us diagram branches, so to speak, in our novelistic tree. Flexi-pages only alters the sidebar nav, and doesn’t give us links to previous and next pages. We also need to be able to rearrange a series, because we often write an episode that takes place between two already-written episodes… I would love to use inseries, but it works with posts not pages…