I have two cats. The one that was here first, is about 9 years old. My new one, about 2 years old, is about half his size. When I try to play with him, he looses interest when she comes around, and starts wanting to play. For example, I was playing with him, and then she woke up from her nap, came in to play with the toy as she heard it, and started interacting with it, and then my older one seemed to loose interest. How can I ensure that he gets his fair share of play, without having to worry about her butting in?