sibling dispute

My wife's parents both died a few years ago, and there is a small piece of land left to the 5 children. They have been unsuccessfully trying to sell it since then. Now one of her brothers wants to buy the others out and build a cabin on it for his family. Everyone is for it except for one sister (who doesn't get along with that brother). Since 4 of the 5 want to do it, can they proceed without the other sister's permission or can her holding out prevent the sale from occurring? What recourse do they have?

Is the property deeded to all of the children? Are all of their names listed on the deed? If so, you cannot force her to sell it and no, you cannot convey her interest in the property without her consent. Would she be opened to the idea of mediation? Everything is for sale for the right price.