No never give up. They use their sifting tray in their "play room" but we are having a power struggle over them using it in their main room. I don't know why. So I was doing as you suggested and slowly migrating them in but once they saw and smelled the Carefresh...you know where they went. So I am going to cover the Carefresh with hay so they get used to the hay and slowly take the EXPENSIVE Carefresh away. :) :) You said you mix it together? I am always so busy trying to keep the hay and litter separate. So you are saying, they will separate the litter from the hay they want? I am SLOWLY being trained. I have a friend that wants to sit for them while I am gone coming over today to see if they like her. :D :D I know they will not....they are so spoiled.