F and M have two children and agreed the children would be in F's care two evenings a week and every other weekend, that they would be in M's care at all other times, and that if either parent was unavailable during his or her designated parenting time, that parent would offer the other parent the right of first refusal for the care of the children. F remarried and was deployed to Iraq. The children spent one night and one evening per week in the care of F's new wife (SM). In January 2006, facing another deployment, F requested that parental responsibilities be modified to allow the children to spend equal time with each parent. He also requested that the parenting time schedule remain in effect when he was stationed in Iraq. He asserted that this would be in the children's best interests because it would allow them to maintain their normal schedule and their bonded relationship with SM. M opposed this motion, arguing that F was impermissibly attempting to establish parental rights for SM that SM could not have obtained in her own right, and that M should not be required to decrease her parenting time in favor of a nonparent. The court determined that the presumption that a natural parent has the right to control the upbringing of a child is rebuttable; that the best interests of the children must be considered in determining whether the presumption has been rebutted; and that in the case before the court, the court was required to consider the relationship between the children and the stepparent as well as F's rights. The court determined that F could decide to have SM care for the children during his parenting time and that in doing so, he was presumed to be acting in the best interests of the children. M appealed.