Hi Dominique, You ask where do I go to find specific real estate laws in New Hampshire? In general, perhaps you would discuss your question with a Broker--probably one whose name is on the sign out front. If you are unable to come to a satisfactory answer with that individual, then follow Buddy's suggestions--which follow mine.
As a Broker, whenever I can't answer a specific question, I always call the NH Real Estate Commission. They are busy, but as a state agency, (you are already paying them) and so they will call you back with an answer.