You asked for opinions, so here goes.....first of all declawing is cruel and inhumane. Please
do not have this done to Kiko. Cats use their claws not only to remove the old sheath from their claws but escpecially to condition the muscles and tendons in their front legs and shoulders. Stretching and pulling gives them pleasure to exercise in this way. A declawed cat's shoulders feels like a old 17 y.o. cat that has lost all it's muscle tone. Some declawed cats become biters as that's their only defense.
As for the poor emaciated mom and 3 kittens. IMHO not a good idea for you to try and catch her and her kittens......the only thing you should do is contact a humane society or pet rescue organization and let them trap the cat and kittens
and let them look after them. Even by continuing to feed momcat, she will only have more kittens in another few mos., then what? adding to the homeless cat population, and her kittens will continue the same way..... Even if you were successful in catching her with the kittens, you would then have terrific expenses of looking after them all. You asked, and I think it's better to stick to your plan of getting Kiko vet checked, wormed, and spayed. BTW, good job on the nail clipping.
When you have done that, then think about saving a rescue kitten for a friend for Kiko that's already looking for a home that has already has been vetted, shots and spayed.