Is it right to punish my sister for what she wears to sleep?

Umm I think that ur sister needs to stand up for herself and talk to her mom. It's not like she's out in public. U should be able to sleep in whatever is comfortable. What ur mom did was extremly wrong and terrible. I think u, and ur sister should trun this on her and make her feel bad. Then she might apologize. Idk what els to do sorry. I'm only a freshmen:/