Mom, I would suggest live traps for the varmints but you'd probably get all cats
I guess an INGO meet & shoot with varmint rifles is in order...
I've got two live traps. Marshmallows smeared in peanut butter is an excellent bait that the cats won't go for. The traps are currently under a mound of snow and frozen in place. We still have at least a foot of snow in most spots in our yard...more where we had to pile it when we shoveled. I've had nights were I emptied the traps before going to bed and had them both full again the next morning.