I agree with the previous answer. But, make sure you think through the full consequences. If they are tenant homes, and your family, for whatever reasons in the next few generations, WANTS to sell the farm, or portions of it, it will be likely be more valuable if it has been subdivided. It sounds like your intention is to keep the farm in one parcel for as close to enternity as possible, and that is respectable. However, you don't know what surprises life and society might bring to your children and grandchildren. Obviously, you love your children and want to help provide for their futures or you would not be considering this.
Talk through the various ramifications with not just a zoning attorney but also a real estate attorney. And, if possible, find someone with a good crystal ball who can help you foresee the future (lol).