Found a drain pipe kitten and need some food advice.

So as the title suggests, I recently had the cat distribution system grant me with a kitten stuck in a drain pipe outside my house.

Kitten is currently 13-14 weeks old, but I'm concerned about his nutrition. I also have an adult cat who has been eating the kitten's dry food and the kitten has now taken to eating the adult food. Naturally. They both get some wet food in the morning and at night and a little bit of kibble during the day or soaked in their wet food. (They're both male so I'm trying to be proactive about them getting enough hydration.)

Would something like Nulo Cat and Kitten dry food be beneficial in this scenario? Does anyone have feeding tips that helped keep cats with separate diets on the right path?

I have a vet appointment on Wednesday to bring up any questions, and I think the kitten is probably in better care in my house than in a pipe, but I am a ~*worrier*~