Family problems

Hey guys ! I just feel like I need to share this , okay so my mom remarried someone and the guy is really nice and sweet and he has two kids who are 13 and 16. And his sister has kids who are 14 and 16. And their parents swear their “innocent” like it’s so annoying . I caught them drinking and smoking weed on someone’s Snapchat story . And I wanna tell him what his kids do behind his back and he thinks their so innocent but their not . Like it bothers me so much whenever he is at my house his kids just thinks they can do whatever wtf they want . Their mom talks shit about my family all the time and they think their innocent . I just wanna tell him what his kids do behind his back whenever he is at my house because the guy is so nice and I feel bad because they do all this bad stuff . I wanna tell him but I don’t wanna cause trouble because their is always drama with our families . Do yall think I should tell him?