Shared parenting refers to a family arrangement in child custody or divorce settlements, in which the care of the children is equal, or more than substantially shared, between the biological parents. Such arrangements encourage children to know both parents are involved and share responsibility in their upbringing. This is generally considered to be a desirable plan in order to parent children separately. It is, however, still uncommon in situations where Family law practitioners have become involved, which is due to the adversarial nature of the courts. More rarely, shared parenting refers to a similar situation after the separation of adoptive or other non biological parents. Members of the fathers' rights movement call for laws creating a rebuttable presumption of 50/50 shared custody, shared parenting. Such laws require parents be directed to develop a mutually agreeable parenting plan. If they are unable to do so, judges order an equal time-share of physical custody between the parents, unless it is not practical or in the best interests of the children. An otherwise non-custodial father would therefore spend more time with his children, increase his caretaking responsibilities, and likely pay significantly less child support to the other parent. Fathers' rights advocates note that the presumption for such shared parenting is rebuttable and that custody decisions would still be based primarily on the best interests of the children. The United Nations Convention on the Rights of the Child has been linked to the idea that sole custody should only occur when it is in the "best interests of the child". Shared parenting has also been referred to as "balanced parenting" or "equally shared parenting".