It seems to me there is a page where the slots are slit to the binding center and can be added quite easily. I will admit it has been a long time since I have seen them and it may be dino technology now. The pages could be numbered as xx-A, xx-B, etc, and replace index pages to reflect the changes. The old pages are simply ripped out and replacements put in their place with the sitted holes. The ones I had used in the past held up quite well as I remember. Just a thought.