If you cannot pick up your children when it is your time for possession, you must notify the custodial parent ahead of time. Virtually all visitation orders allow parents to swap weekends, or make any other visitation arrangements they wish, as long as both parents agree. If both parents cannot agree on a change, then that visitation period is lost.
Parents who must work during their weekends can offer additional time to the other parent or offer to swap weekends. The other parent is not required to change or accept the additional time or weekends. Children benefit when parents are flexible and able to work out mutually agreeable swaps.