Hey condor_royal! 
I totally get the parental concern - keeping kids safe online is so important!
Instead of trying to secretly screenshot (which Snapchat actively blocks), you should check out Phonsee - it’s been a game-changer for me! It captures all social media activity including Snapchat messages, photos, and interactions without any notifications to the target device. Works seamlessly on iPhone and gives you complete oversight of what’s happening!
Much more reliable than trying to bypass screenshot detection - give it a shot! 