That's fascinating! What does Aris do that means she's noticeably better at mom duties, is she just more interested in the babies? What are the sorts of things you can do to support Heather, you've obviously got the excess wet food, but do heat lamps help, if Wendy joins in will that help? Can babies learn from each other as well as mum, will that help?
Aris is just more anxious. When a bird gets a Lot of babies, I think the tendancy is sometimes to assume that the crying one is not yours, because you can't count and you have a lot of babies right next to you, so OBVIOUSLY you have all your babies. Aris assumes the opposite- EVERY crying baby might be hers, so she checks on her babies AND everyone else's. When she has a lot of kids, this means she keeps them rounded up and I never come out to find one chick roaming around crying while their mom sits on everyone else, oblivious. Wendy is similarly anxious, so she's been checking on Heather's kids. Heather has never had this many, but she's handling it well. There's not really anything I can do to help, aside from making sure they all get plenty of food to grow well, and checking on them frequently to make sure she's doing her job. If I have to intervene more than that, it will be to take chicks and raise them away from her, and I don't want to do that unless I absolutely HAVE to.
But, they all had their chicks at the perfect time of year for my location- june is typically the latest I want them to hatch. This is because it's hot practically constantly, and will remain ambiently hot for the next 2-3 months here, giving them time to grow without needing mom's heat quite as much (except at night).
Heat lamps aren't useful, or safe, especially around birds that flush. But they straight up aren't useful, because the babies need periods of being cold. I'm not saying they need to be freezing or need to get so cold it harms them, but periods of being uncomfortable alongside proper warmth from mom mean that their systems grow in feathers at an appropriate rate to keep warm on their own. Constant heat, like in brooders, can slow growth. It's needed, for about the first week, for them to be warm almost constantly. Mom will sit on them a lot. After that, their feather growth should be such that if they HAD to spend a night next to mom instead of under her, they could start doing so by around a month old. That's about the time when it becomes difficult to keep more than 4 chicks under a single hen. Corona is pushing that limit right now with her 4, they are barely fitting under her and starting to consider sleeping next to her. She's started sleeping next to Aris (her mom), so that the space between them is warmer.
Aris is perfectly willing to look like a fool, though. She'll sleep with her wings flopped out over a bunch of babies long past when she has to. Her babies are always VERY well covered and cared for.
As for learning from each other.... enh. The babies don't learn between groups until they start hitting around 2ish months and realizing other birds are other birds and not scary monsters. They might steal food from each other, or run over if one chick looks like it found something tasty. But largely they are mostly concerned with themselves and mom for the first couple months.
