 Remind them that most dogs can bark from boredom. Suggest they try to control the barking with providing the dogs with more exercise. Like instead of letting them outside, maybe they have time for a morning or a night walk. You might even suggest that they pass time with the dogs while they're outside. They could be playing with them or doing some training with them. And depending on their reaction as well as their ability to take charge of the situation could determine your next move.