If you wish to keep the business in the family, it may be necessary to prepare a buy-sell agreement between the owners. This is not a simple matter. Recent changes in the law have made it difficult if not impossible to determine the price of a closely held business that will be recognized for estate tax purposes.
It may be that all you really need is an option to purchase the stock of the other owners upon their deaths since you can control the disposition of your stock under your will. On the other hand, a funded buy-sell agreement could provide your estate with the necessary liquidity.