carpedebass, Yes they can do that but if your group understands that everything that is happening in a SHTF time(total collapse) every thing that happens maybe part of a coordinated offensive. I would not take lightly even a child coming my way in a time like this.
So you would have one or two in your group look over the child, the rest of the group is on the lookout(high alert) at the time. If the child looks like they are lost or there parents were killed then you are to still stay alerted for days after till you see that there is no sabotage planed by anyone.
But in the cities I see that all groups that are alive are targets because it means that there is food and water.
One problem I see is in your own group will everyone agree to take in a child or will they shoot everything that moves since they have been shot at by many and feel that everything that moves needs to be killed, no questions asked.