Access is required to be provided to the cemetery if the company doesn't move the graves. If they do move the cemetery, I believe they are required to notify families and it is recorded in the clerks office so families know where their loved ones are removed to. As for your sister, I'd hold on to it too. Property that has been in the family for a very long time has more sentimental value than monetary value. If she choses to sell, maybe she can ask to retain the property which contains the cemetery and have them contract that they will provide safe access outside of the mining area. It all depends on the location of the cemetery to the seam of coal they intend to strip. It wouldn't hurt to ask. If they want the property badly enough they will work with her.