How tragic! I am so sorry for your guys. The foxes living on our property moved off three seasons ago, soon after we got dogs. We just got chickens and now DH spots a nice, healthy fox in the woods behind our house!
We are locking the kids in the coop at night (predator proof), keeping them in a pen in the day time when unsupervised (not predator proof, but within areas marked by the dogs), and allowing them to free range when we (or our black lab) are watching them. I'd love to be able to leave the dog door open, so our lab can watch them day and night, but my coon hound annoys the whole mountain with her barking, and the dogs don't like to be separated.
We are avoiding trapping or hunting the fox since it hasn't yet caused us any loss...giving it a fair chance, you know. But if it decides to try and get some chicken dinner at our house, well there will probably be a new pelt drying on our porch pretty swiftly.