Friends working for free have rights?

[Alex Howard]

So in my current flip property we have my partners step dad coming in and volunteering his time working on the house with us. Sometimes we are not there and he brings his wife to help or just keep him company. My father is concerned that this gives him the ability to lay claim to money either for his services or money when we sell the property. I am under the impression that since there is no written or oral contract for payments there is no issue. We are in Ohio if that helps.