As a non-custodial parent, I always keep the divorce decree, any agreed upon items in writing signed by both parents (or the email trail showing the same), copies of their birth certificates and the photos. I also have them have state Id's just because -- even though they are under 18.

When you've been falsely accused one too many times, you OVER PROTECT yourself (even though you shouldn't have to!).

When I've traveled in the past with my kids across state lines I have a huge file folder of all this with me, a digital copy backed up on two hard drives, a copy in the cloud and a list of important phone numbers I can call, like my parents, other relatives I'll be visiting, the other parent's phone number, court case numbers, lawyers and the non-emergency phone line to the law enforcement in the area I'll be staying (in case I need to follow up on getting reports, etc.).

I'm armed to the teeth with paperwork. If you're in this situation and something like this happens, you're going to be so angry, scared and stressed out you will need those phone numbers written down on paper in your face so you know who to call for help.

I can't wait till we just can put all of this on a public, permissioned block chain, have those in power verify what you're saying is true and flip both middle fingers straight towards your false accuser -- no matter who that might be.

Edit: I don't care who the false accusations are coming from. The resulting fallout is all DAMAGE and the allowing of it needs to end.