prom after party stress Options

[Ahmanduh2]

Okay so for my prom group, I found a rental house where we can all stay the night at, which my mom has agreed on. My 20 year old sister will be staying at the house to chaperone But the only thing is my mom has the rules (which i knew were coming)

NO DRUGS, NO ALCOHOL (SHE STRESSED THIS ONE THE MOST), NO SEX.

And of course the people in my prom group want alcohol. At our prom meeting there were all discussing all the drinks to bring (vodka, bacardi, things to mix drinks and etc.) I really don't mind if they want to drink just not to the point where they are puking, even though I will stay perfectly sober. My mom said that if they drink alcohol and drink too much and get sick and have to be hospitalized my mom will be resposible which is true. But I would never let anyone's drinking get that far. I know I can make sure my friends dont go out of control with the alcohol.If I have to I'll limit their drinks. I don't even think a lot of them drink a lot. But that still doesnt solve my problem. My mom is the one who asked my sister to chaperone and make sure there is no alchol and etc. I would think my sister would know what situation I am. Maybe she was in my situation back at her prom after party, maybe she even drinks.. I dont know. I have to ask her if it's okay if there is alcohol cause it's gonna be hard to tell everyone we can't have alcohol. People are gonna be disappointed that we have a house and they cant even drink.

Sorry this is long. Any advice would be helpful. Should I talk to my sister? Should I just ban any alcohol? Should I talk to my friends? Or I don't know.

if only 18 was the legal drinking age..