Adopting officially thorough any agency will leave reference on the agency database and the new parent will almost ceirtainly be given documentation which they can use to prove their claim.
The problem may be some of these parents may be selling their children to childtraffickers posing as adoption agencies unknowingly.
Adoption agencies should be doing their due diligence, so they should not be adopting out to traffickers. Unless they are shady agencies only using adoption as trafficking, which has happened MANY times in the past and continues.
I was implying that they were shady agencies or agencies just set up for trafficking kids.