Quick answer
Ask about a formal modification when important circumstances change; do not assume a new routine silently replaces the order.
Do now
Identify what changed, when, and how the child is affected. Draft a workable replacement schedule with transportation and holiday details. Keep evidence supporting the change and any safe efforts to resolve it.
Watch for
The legal standard for changing an order differs from making an initial order. Continue following the existing terms unless changed by valid agreement or court order, subject to urgent safety advice.
Official sources
NJ Courts — FD modification application packet, NY Courts — Custody and Visitation, DC Courts — Family Court Self-Help Center.