You keep saying him and them and it's confusing. Are you saying your hatch on Monday only had one success and it's a roo? How old are the other chicks if you say they're "too big"?
I think a good solution would be to put the two brooders next to each other but I don't know what you're using
The “him” is for not getting my hopes up that it’s a pullet. I actually wouldn’t mind having a son from this rooster. (Lavender Orpington)
The “them” is for the older chicks, who are two weeks older than this new one.
Yes, only one hatched this week. I think when “he/she/it” gets to be a week old, it will probably be fine to put in with the older chicks. I just didn’t want to take a chance until it got it’s sea legs.
Yeah, it’s not possible to brood them where they can look but not touch. Most of my brooders are plastic storage totes. So even though I put the brooders next to each other in a row, they can’t see each other.
But the good thing is that I put some really small crochet chickens that I had laying around under the heat plate with the singleton chick, and now I rarely hear him cry.

I have named him “Kempson” btw, in case he really does turn out to be Kemp’s son!
Kemp is one of my favorite roosters ever. Everyone who visits always points him out and says they like him best. (Out of 50 or so birds visible from the house.) People coming to buy chickens always try to get me to sell Kemp to them. No way! I should post some photos of him.
Oh, and I may have found some friends for Kempson. The one CL ad I had found who I thought was ghosting me, actually responded this morning. (Two days later) So it’s possible we may meet up. But they are only communicating through the CL relay email and that’s really cumbersome. They obviously don’t care that in my initial inquiry I said I needed to find chicks ASAP and gave them my phone number.