and thank you for adopting multiple cats! That is wonderful that they have been tested, neutered and gotten their baseline innoculations -- that's the right way to start out in life. We hope you enjoy the forums and are able to find lots of good information to help you and your cats enjoy a happy, healthy and safe life together. Lots of times, patience and a little bit of showing them (by taking the scoop and covering completely before they leave the box) is all that's needed to get the habit. Love and patience are always the key!