Do you want a how-to? You could read the article I wrote on brooding chicks outdoors, which also includes how a "panic room" works to make integration easier. It's the second link below under "Articles". Pictures included.
I suggest you not try to do all three age groups at once. It would likely drive you to drink.
Your first challenge will be to integrate the two chick groups. Remember for the future, if you get more babies a few weeks after getting the first chicks, it helps tremendously to raise them side-by side. That's the first step in integration - introducing them to each other.
After a week of being alongside each other, try letting them mingle. There will likely be some pecking and minor conflict, but generally it ought to proceed fairly well. If you notice one or two older chicks being persistent bullies, I have an article in that bunch below on how to deal with that, too.
Meanwhile, if you rig the chick pen in the run to accommodate chick-size openings, approximately 5 x 7 inches, it will provide a safe refuge for all the chicks when you let them mingle with the adults. Those size openings will accommodate chicks to age three months.
Place the chicks' food and water inside the safe enclosure so they will be assured of not being chased away from essentials.
In addition to the panic room, try to have as many perches in the run as possible, as well as horizontal and vertical surfaces for evading large bullies.