And why do you want to board somewhere where they let themselves get taken advantage of? Why didn't they tell the people no you cannot bring another horse here, regardless of how you got it, until you are caught up on board bills?
Their carelessness is going to affect not only the barn owners but also you as a boarder? Will they have to cut feed or get antsy about turning off lights because three horses live there for free???
"Equine-facilitated therapy employs a form of biofeedback for practicing self-awareness, emotional management, and relationship skills that human role-playing exercises and discussion groups cannot begin to access." Linda Kohanov (The Tao of Equus)