I whole-heartedly agree with everybody: Declawing is barbaric, and it will cause problems with arthritis in those amputated joints.
It also can change a cat's behavior. In our clinic, I have seen many cats turning into fractious animals because of the procedure. The older the cat, the harder it is on them. Please, please reconsider.
Your veterinarian will apply soft paws for you, if you can't do it at home. They will stay on until the nails are getting long again, and they will last anywhere from
6 -12 weeks.
How do you know your kitties would chew them off? Have they had soft paws before?
You could also ask your vet about calming meds you can give in the evening. Or if you prefer something more natural, you can try composure treats, and you can try Feliway, a synthetic pheromone.