We need a plugin that will allow us to GROUP POSTS.
Each post will have a PAGINATION at the end of it's contents (front-end, visible to site visitors).
PAGINATION will consist of links to other posts in a group (either "page" numbers or post titles - this should be an admin option).
Admin can add posts by clicking on some BUTTON in the post add/edit area in the wp-admin, upon clicking it the current post will be saved standard way, but additionaly assigned to a group + NEW POST page will be loaded up (this NEW POST will be assigned to the same group upon the BUTTON being clicked - as well as - when it's published/updated the standard way - using the WP built-in button). Posts must remain in the same group upon being saved either way. Post can be only in 1 group.