My husband and I recently got a new kitten. They have each been using their own litterboxes because they've been separated up until recently when they've gotten used to each other. Even when they were both out they were still continuing to use their "own" litterboxes. Then yesterday Oliver (the baby) used Bagheera's box. She doesn't seem to have gotten upset by going to the restroom somewhere she shouldn't, yet. Should I worry about her getting upset by this? Will they share litterboxes?