Yes, take the babies away. Before she kills them, or something else does. If they're avoiding her, she's given them very good reason to do so. Most babies don't have the sense to avoid a hen who is killing them, it takes a lot to impress upon them that their mother is rejecting them.
If I were you, I'd reintroduce them at night to the Rock and watch carefully early in the morning to see if she will accept them. If not, raise them yourself, or whatever you want to do. I would keep them outside their earshot during the day, and whenever handling them, hold them securely in my hand (both hands if necessary) so they snuggle and do not cry. Cupping a hand over their heads and backs tends to provoke the snuggling reflex in them.
When the chooks hear them crying, they are identifying them by voice and if you want to try to introduce them to a potential foster mother it's important she does not first identify them as 'not my chicks'. There will already be some confusion due to the mixed mothering/brooding, it's not recommendable, it usually results in trouble. Not many hens can co-brood or co-mother.
At night, soon after dusk so they have the most bonding time possible before the hen can see them, I would introduce them to the Rock, holding them securely so not only can she not see the chicks being put under her, but she also can't hear them calling. Most chicks will have the instinct to stay quiet for a while, then assimilate with the current clutch by gradually introducing themselves to the mother by building a bond via vocalizations before attempting visual bonding. Normal mother-chick voice bonding begins to occur as they are pipping the shells, so there's a good chance the Rock is partially bonded to them already, if she was present as they pipped.
The orp is showing you she lacks sufficient maternal instinct. Breaking her off the brood is about all you can do. Not only will she harm chicks but she will brood empty nests --- that's about as 'dud' a mother as a hen can get, it's one step below a hen who's never brooded because a hen who has never brooded may still reveal complete but delayed maternal instinct. I've had old hens suddenly reveal a maternal side they never showed before, like pros despite lack of experience. But bad mothers are something else. I would not waste chicks' lives on her deficient maternal instincts. It's unfortunate but all she will likely be is an occasional egg-layer who possibly presents a threat to chicks and takes up your time in repeatedly breaking her off the brood.
As a side note, I think you may have removed the extra eggs too soon. 21 days is not a golden rule --- they can hatch days earlier or later than that. I leave the extra eggs until the hen leaves the nest, sometimes even leaving them longer than that, and many still hatch.
They may have had their 21 days' worth of incubation staggered over a longer period because they were left cold overnight or during the day a few times; hens with incomplete maternal instinct are good at creating this situation, and co-brooding is too. A hen without the sense to tuck eggs securely under her is generally one way you get this issue.
When let to chill the eggs don't die, they simply cease growth temporarily and go into a kind of metabolic stasis until sufficient heat returns for them to resume development. Contrary to what so many people are taught, stone cold eggs are not automatically dead eggs.
This interrupted brooding pattern can persist right up until they're pipping without killing them. Both chicks and eggs can become stone cold and still survive. I've had a few clutches left cold overnight through winter for the duration of their brooding which still hatched; bad mothering was responsible, they had clutches hidden in the forest and came back to roost in the main cages every night so I thought they were merely free ranging during the day. Some of those eggs were quite a few weeks old and still hatched. It's not ideal, and it does make skinnier chicks when they do hatch because it was a bit of a marathon for them, but it's survivable.
Hope this helps. Wish I'd seen your post sooner, you've probably missed your first opportunity to foster them out under the Rock. Best wishes. Hope it works out for the chicks.
