I'm the older bro, basically me and my 2 siblings ( none of us smoke ) all live on the first floor while there's my parents room and my younger brothers room up top on the second. My dad essentially invited there friend over as he recently divorced and has became homeless to help fix up the house and help get him back on his feet.

He's been smoking in my little bros room ( who's around 10 ) completely ruining his room. It's been like this the past 2 weeks and it's driving us crazy. He doesn't open windows or even tries to midgate it any way. We've tried talking to my parents about it but they refuse to make him stop and the guy gets angry that we're bothering him about his constant smoking in the house.