I've already kind of done something like this to encourage Questers to seek out other cards XD Things like seeking out a card with a book on it, and the name on the back is the name of the new pet, or finding a map piece that has water on it to connect to one path so it puts out the "fire" and you can go in that direction.
If someone else is willing to design stickers, I'll happily connect some of my cards to it all! Having stickers that include something with fire, water, plant, and book would be of particular interest to me and would take some very minor tweaking on my part to incorporate them.