Not-really-halachic question about shechita

I’ve raised and shechted many chickens before, but this year I have a new situation.

One of my hens went very broody. She wanted babies so much. As I don’t have roosters, I purchased some viable eggs and popped them under her back in…early August, I think. She hatched them and still snuggles them under her at night now that it’s frosty. They’re fully feathered and …teen chickens now, I suppose. Not sexually mature (they don’t lay eggs/crow), but basically they look like scale-model adults.

Shechita time has come, but I’m not sure what order to do this in. I have six total chickens (two sisters; will need to be dispatched the same day as they’re pretty bonded). One doesn’t give a damn about the others. Then the mother and two teens. I don’t especially like doing more than two at a time because it’s cold, messy, and I don’t have the kitchen space for salting/soaking/draining many at once.

Obviously there’s no halachic thing, at least that I’m aware of, about reducing the emotional impact to the chickens beyond not letting on what’s going to happen. I shecht them out of sight of the others, but not out of sound – and mother and teens are very concerned about each others’ calls.

(chickens in general are not bothered by it other than sound – they will happily eat other chickens/bits of chickens.)

I expect I’ll have to do mother and both younglings at more or less the same time – but who goes first?