Notify schools, day care centers and babysitters of custody orders, give copies to such caretakers and ask to be alerted if the non-custodial parent makes an unscheduled visit to the facility.
File a certified copy of your custody decree in the non-custodial parent's home county (state). This notifies the court in that county (state) that a valid decree has already been issued and must be honored. Also consider filing a copy with counties in which non-custodial parent has close friends or relatives.
Keep lists of information: addresses, phone numbers, social security number, passport number, and birthdays of all relatives and friends of the non-custodial parent.
Keep current photos of your child updated every four months. Know their current weight and height.
Keep all information in two separate and secure places.