If I was in this group of friends I would feel upset because they all wanted to pick on him. If I were Jan I would tell them if they aren't going to be nice then they should just not stay ans talk with them. I would have let Chris join the group of friends. If they bullied him it might push him to kill himself. Everybody is just better off being nice to everyone else.
Chris is probably a kid who is different that not many people get. Most of the time when you are different many people will just bully you because you are different. But when you make that person your friend it can sometimes just might save the life of an innocent person. So just don't bully, instead keep your school peaceful.