Ds1 has a friend who is two years older, and I have just had to step in and remind him that my son lives here, he is allowed to go upstairs when he wants, he is allowed to play with his toys etc
he's a nice kid, but it seems his house rules are very different, in that his older brother is left in charge for what (IMHO) is a too-large amount of time - and he seems to assume that because he is the oldest in the room it's up to him to keep everyone in line.
My house rules are that nobody gets blamed for what other people do, and siblings are not in charge of each other.
I have told him that he doesn't have to worry about what ds1 is doing, I will never tell him off for what ds1 does, I would tell ds1 off not him etc, but it's not registering.
Visiting child is 7 BTW - is it just his age? He's a nice boy, I don't want to stop him coming round, but Ds1 is getting pissed off with being told what to do all the time!