Hiya, and welcome to BYC!!
We have your situation (almost) with some 1, 4, 5-year-old birds in the main coop who all free range as well as the 4-month-olds and the 2-month-olds.
There never is an issue until I bring out the ferment/treat so I have to lob it out in about 10 spots so everyone gets some without others being pushed away. Otherwise, other than feeding frenzy, they stay out of each other's way.
At coop time, the 2-month-olds go to their temp coop and all the rest head to the main one. Tomorrow, we'll do it all again.
To keep ants from the coop and the house, I sprinkle food-grade diatomaceous earth around both. Redo that when it rains. If I see an ant in the house, I know I forgot!