I would only ever treat a seller with the respect that they deserve, remember if you are a buyer you will one day be a seller. I have bought and sold many boats, and have always been as up front and helpful that I could be to the buyers. If I felt I was being treated like this - you would not buy my boat, and if you did, There would be nothing outside of the inventory listed, left on the boat when you took possession (hope you have dock lines and bumpers listed on the inventory, or fuel) (Spares we all have them), when we sold our last sailboat, we had a guy try to use a surveyor to negotiate the price down, with ridiculous findings, (boat needed new standing rigging because it was 17 years old), this came back to bite him as we said no way were we doing anything with the rigging, and after he agreed and proceeded, he could not get insurance, on the boat due to his ridiculous survey, (he had to pay for a 2nd realistic survey, after he closed the deal.) and after the close, when I had my money you could whistle Dixie when you had a question. Just my 2 cents. If you are using a Broker, (which there are lots of reputable ones up here in Canada), get him to negotiate with both sellers on your behalf, and enter into a contract once he has finished negotiating for you, that you intend to bring to fruition, (as long as all terms and conditions have been fulfilled) Cheers