The answer is: "Yes, if she could make a clear showing that the natural Mother had abandoned the children and was an unfit parent. Failing that, she could get visitation since her son is deceased."
The recent Mississippi Court of Appeals decision of Pruitt v. Payne, No. 2008-CA-00172-COA (July 28, 2009) is instructive. In that case, the Court of Appeals affirmed a Trial Judge’s decision to dismiss a step father’s petition to enforce an agreement with the natural father allowing visitation for the step father. The Court stated that custody and visitation is controlled by the Legislature, which has declined to extend custody or visitation rights to any third parties, except grandparents in particular cases, such as where their child is deceased. The Court observed that this rule is so strictly enforced that half siblings do not have the right to seek court ordered visitation with each other. Scruggs v. Satterfiel, 693 So. 2d 924 (Miss. 1997).
Without an agreement–which apparently is taking place–Michael Jackson’s Mother would have to file a petition and successfully show that the natural Mother of the children would be "unfit" to have custody. Such proof could include a showing that the natural Mother abandoned the children. This proof would have to be clear and survive a strong presumption in favor of the natural parent. In Re Guardianship of Brown v. Wiley, 902 So. 2d 604 (Miss Ct. App. 2004). If Mrs. Jackson were not successful in obtaining custody, she would certainly be entitled to visitation under Mississippi’s Grandparent Visitation Statute.