Either remove children, Make them incapable of alerting, or Allow children to be killed/knocked out
As it stands right now, children act as invincible security cameras that the player cannot act against. They will alert guards without the player being able to do anything to prevent it.
1) Remove Children, replace them all with young adults.
2) Make Children incapable of reporting crimes/events (make adults not believe them, etc).
3) Allow players to knock out or kill Children.
IMO #3 is most in-line with the game's premise of "go anywhere, kill anyone". But if that is in poor taste for the developers, then #1 is probably the best option. #2 is a compromise that'll solve the core issue.