My Kitten Isnt Growing My Cat Gave Birth To 2 Kittens One Isnt Alive. When Should I Allow Mom And Baby To Be With My Other 3 Cats?

My cat gave birth to 2 kittens one isnt alive. when should i allow mom and baby to be with my other 3 cats? - my kitten isnt growing

I have 3 other cats. Now mother and child are in my bathroom apart from the others .. I do not know when to get back to my bathroom. The cat is now a week. IM is also afraid that the mother is not enough for the kitten I'm look worried? o What can I do. the kitten is growing rapidly.