Since you do not say, I presume that the parents of the children are in an intact household, and that no court anywhere has ever issued an order of any kind on the subject.
If so, then the grandparents do not have any right to even ASK for visitation, in or out of your home, beyond whatever access you choose to give them. NRS 125C.050.
If there has been a death or divorce, or certain other facts, the presumption is still that you can do precisely what you wish, including all denial of contact, and it is an uphill battle for any third party to overcome the presumption that the parent's wishes are to be followed, as a matter of Constitutional law. Further details at http://willicklawgroup.com/child-custody-and-visitation/. If you have further questions, you should consult with a family law specialist.
Answered on Sep 01st, 2013 at 5:40 PM