No one is eating their correct food!

We have a new addition to our family. The new kitten is #3 our oldest is 10, the middle is 2, and kitten is about 8 weeks. We rescued kitten from our property. Anyways, the 2 year old keeps eating the kitten food, and the kitten keeps eating the big girl food. I try putting out the kitten food twice a day, but if she is hungry before then she just eats the adult food. The 2 year old who is a bit chubby keeps eating the kittens food she sniffs it out as soon as I put it out. Any suggestions, or ideas would be helpful. I'm about fed up.

to TCS Can you feed all of them at fixed times, rather than free-feeding them, and separate them during meals? Have you thought about switching to an all-stages food so you can feed them all the same thing?

You need to switch to timed feedings. Give the kitten more feedings. I have 7 cats, they get 4 meals a day. I watch them while they eat so they only eat their portion.

I was going through a similar problem with my adult cat and new kitten- I just gave up and started mixing the cat and kitten food and they do fine (kitten is a healthy, chubby girl and adult male is a responsible eater and hasn't gained any extra from kitten food). I understand this is probably not the best choice for a senior cat however as they need less protein and fat. is there any way he can be fed separately?