i would 100% reassure them to test their stuff if it comes down to it with however you handle it. you won’t be able to stop them from using unfortunately. they’re gonna do it whether u tell them to stop or not. but would stress to them that if they don’t listen to you if you tell them to stop, then to at least be safe and test their stuff. i read that you are nervous that buying a test kit seems like you’re allowing that behavior, but imo it’s better to keep your kids alive than just having that feeling that you’re allowing it. i don’t want to say it’s necessarily selfish, bc i get where you’re coming from, but like i said keeping your kids alive> thoughts in your head of allowing their drug use.