A couple of things come to mind, all protective, were your concerns in the contract? house, pond, the 7th owner roadway house clause? Have you consulted a local real estate attorney? Has the deal closed? Regarding the Realtor, was he/she aware or should have been aware of the restrictions? 6 lots sounds like a subdivision and a subdivider, what were their claims, advertisements, brochures? What were the other 6 buyers understandings?
I mention all of this because it looks like a legal situation, which suggests legal help, asap.
