I'm not sure I understand the question. Can you clarify exactly who lives/works where? Which three people split the 3 rooms?
In one scenario, you own the house and rent out two bedrooms and your home office is the other bedroom. What about common areas?
Common areas are not rental space. They belong to the landlord. In this case, this is personal space that can't be included as rental. If you are self-employed and meet the qualifications for a home office, then you can prorate the square footage of your office contrasted to the square footage of the entire house, just as you would do as if you occupied the entire residence.
