Agree with
Norachan
on mom may need a vet check.
She doesn’t to be bothered by the nursing itself it’s just once the kitten gets close she attacks/then grooms but after a bit or when she’s distracted she doesn’t mind the nursing at all.I am glad to see the good update! I would definitely keep the other cats away.
Mama kitty's behavior towards the baby is indicative that nursing is causing her pain or discomfort. Are her nipples looking sore? A thin coating of coconut oil might bring relief. However, it could be a deeper source of pain, perhaps impending mastitis or even a bit of tissue not properly expelled during the birthing process. I concur that a vet exam is in order; ask the vet's office about offering sedation - I know it ups the cost but maybe you could get donations to help.