Now that you mentioned how to refuse, it means that your family doesn't want to sell the house to this relative. The subtext is that although the relative is real, the relationship is not good or the relative just wants to buy your house cheaply and pick up a big leak. And your family doesn't want to suffer such a big loss. Who has a problem with money these days? Understandable.

Since you are not going to sell it to this relative, just make a particularly high price. Even if you look at the face of relatives, the preferential price is too high, which will make him not buy it. If you don't want to offend him, say it has been sold to someone else and sign a contract to pay the full amount. If he doesn't perform the contract, the penalty is very high and he can only be helpless. This is a safe thing to do. Find a reliable acquaintance as a house trust, and try to make it look like the real thing, so that relatives can't see the flaw, so he has to give up. Then secretly find a good buyer. Relatives can't always stare at this house anyway, can they?

Finally, I wish you success in selling the house!