Part of family business left to people not in the family?

A family has a family business. It was left to 3 of the original owners children after his death. It has been discussed about selling withing the next 5 years or so. It has been operated for 70 years. Quite successful, until the economy went bad. One of the current owners recently passed away. Being the youngest of the 3, he didn't plan on passing first. He was going to redo his will, but didn't get around to it. His portion was left to his deceased wife's kids and her grand kids. Not ideal, but it is what it is. Now, an expense has come up and the current owners need to contribute some money to cover the issue. The new owner(s) refuse to contribute. They are insisting on selling. Not just their portion, but the whole business. They are not willing to wait until the economy recovers in order to get a fair price. They are wanting the money, that they figure is theirs from this business. What rights may the other 2 owners have?