How do Addon Pages interact with existing Pages of a game?

Im building my first addon product. I intend it to have several map pages but Im not sure how those pages will be listed/organized in the page toolbar when the addon is added to an existing game. Will they just be add added at the end? or will the addon's pages be mixed in with the game's pages in alphabetical order? Or something else?

Something else.  By default, all pages are in Page ID order. Page IDs are unique IDs that are generated based on the date. So basically, they'll be in creation order. That means adding to a Game wholly created before your Addon, they'll be at the end. Added to a game while crated after your Addon, they'll be at the beginning. Added to a Game created before your Addon but with pages added after, they'll be mixed in.  Probably to be safe, when you have finished creating your Addon, you should Transmogrifier them all to a fresh Game so at least they'll be all together and in the right order.  This is of course just observational information. It's possible they've fixed this, but I'm guessing not.