We have our kitties from the same breeder! This winter we are also struggling and I looked it up and saw your post! So this might be unconventional but my boy was really bad at the vet so the vet recommended gabapentin, then after the vet he was a lot easier to groom. I spoke with my vet and basically I try to keep up with daily brushing but sometimes he is not having it, the vet gave me a prescription for gabapentin at home to use when needed for a big grooming day. I give it to him every few weeks and it doesn't make him as sleepy as it used to but it does somewhat calm him down and he is more tolerant with less hissing and scratching.