Bella and Zoey would have eaten them. End of story. Psyche, probably would have been scared of them, but honestly, that's a HARD situation for any dog -- because not a lot of us have the experience to say if our dogs will be okay around two random ferrets. If he's going to be bringing them back continually, I'd talk to him. Mention to him about how you're worried your dogs will have an issue, and see if there's a way for you to compromise. Might be hard to get near him to talk to him, though, if you've got your dogs and he's got his ferrets.