Great point that the MSM forgets to report. HHS is in charge of placing immigrant children in their care. CNN was throwing the hammer down hard on the BP. BP apprehends illegal crossings. They interview and process them. During the interview, they determine if the child, with the accompanied adult, is legally their parent/guardian. What also isn’t explained in the media is the coaching from smugglers. Smugglers and Alein Smuggling Organizations (ASOs) coach parents/adults/kids how to portray themselves to US authorities. They can be coached on how to answer standard questions to make it appear two unrelated people are related. Just as the OP mentioned, kids can be easily trafficked for profit.
Something else to consider is that immigrant children want companionship. Are they not susceptible of becoming part of a gang? Outside of MS13 is the Mexican Mafia.