Should you declaw them make sure it is only in the front. If they are not fixed yet that would be ideal to get it all done at once to minimize stress on the kittens. It is your choice so don't let anyone else tell you other wise. All my cats have been declawed in the past and have all been very healthy and have lived long lives.

Declawing is a very painful thing to do to a cat. If you are going to have it done please research laser declawing it is much safer and less painful with a quicker healing time. The kittens should not be declawed unless they have behaviors which would require to have it done such as destroying things by scratching or scratching people or your other cat.
Also, cats that are declawed are more likely to start biting since it is now their only defense.