The other aspect of this is the definite possibility of the child having been prepped to mitigate any security that has been put in place such as unlocking doors in the night, use of flashlights during light discipline designated times, noise, etc. This was common for Vietnam soldiers/sympathizers to do. They would drop off orphans to US military bases with just enough instruction to turn on lights, yell/scream at night, etc. It cost many soldiers their lives.
If this is something that you plan on doing (taking in youngsters) then you better prepare before hand to take care of them. They better be all but quarantined and watched 24/7 until they get totally integrated into your family.