You can use brads to attach them. Vellum tape can also be less noticable than d/s tape. If it is a 12x12 overlay, I don't usually attach the paper behind, I just have it sitting there and when it's in the page protector, neither bits move. Depending on the overlay, you could use corner stickers on the top to kind of hide d/s tape. Hope this has given you some ideas, if you need any other info just ask!