Smelly Cat, What are they feeding you?

The addition of a new kitty to the household has our two older cats in a tizzy. Ruby and Maxine are about 13 years old and sisters/litter mates. We had some experience with trying to introduce a new female into this setup a couple of years ago. That's why we chose to get a male kitten. Ruby is old and fat and Maxine is as skinny as a rake and feeble. They don't really even like to tussle with each other anymore. Poor Dobby just wants so badly to join in cat games. At least he doesn't seem to be bothered when the grumpy older cats hiss at him and run off. He's only about two months old and all of 5 ounces at this point, about one sixth the size of the two older cats. He just keeps chasing them. Last night he was trying to engage Ruby and she was fleeing as best she could with her fat kitty utter swaying from side to side. She came into the master bedroom while we were watching TV and tried to obtain refuge on the nightstand. She failed miserably in attempting the jump. They are just so pathetic.