Hello there Akiko! I feel your notion of acquiring a single device and find out first if all of them get accustomed to the Litter Robotic it’s a good tactic. Then, if the thing is them all working with it, you can purchase a 2nd just one. One single unit https://automatic-litter-box65421.blogocial.com/a-review-of-robotic-pet-cleaning-72638262