Karen Walsh: When families disagree over co-owned land

My father died six months ago. In his will, he left the land between me and my three siblings, in equal shares. None of us are farming. 

There is already disagreement between us as to what to do with the lands. Should we lease it? If so, for how much and to whom? Should we sell it? I do not want to us to fall out.

While we all want to keep the land at present, what would happen if one of us wanted to cash in our share?