Time for your sister to put down some wet food and/or kitten milk for Phoenix. Princess is in the process of weaning Phoenix and so time for Phoenix to get a taste of what kitty food tastes like. Pretty well all the kittens I have ever been around have been started on kitten food about the 4 week mark. Between now & 6 weeks she should be pretty well done with feeding from Princess. Once they start on kitten food you will really see her grow and it doesn't take long for them to decide they like the kitten food even better than mum's yummy warm milk. hehehhehe...Phoenix & Princess are both lovely.