My nephews are due to visit later and I'm dreading it.
They are 4 and 6, as are my two.
Last time, they got quite naughty silly and it was really stressful
For example, drawing with felt tip on the coffee table, then doing it again after having been told not to. The younger one went rummaging in some wardrobes and helped himself to unopened face paints and nail varnish (which I found on the carpet, luckily not a visible colour). There was lots of screaming and whining about wanting to do stuff they couldn't, going on and on and on, and they are much more physically confident than my two, particularly my youngest, which means there is lots of rough play, wrestling, pushing and shoving.
I'm really confident with discipling my own children, and they would never behave like this, or continue to do something after being told not to.
With my own children, I would do warnings and sanctions, e.g. removed from the room or take a sticker off the reward chart, but I very rarely have to resort to these.
I think my SIL is at a loss as to how to deal with their unruliness and lets a lot of things go... Also, they used to pay attention to me when I asked them firmly/sternly, not to do whatever, but they just ignore me now. Towards the end of their last visit my eldest was starting to ignore me too.
This is making me really sad as I do love my DNs, but I don't want them to come if they trash my house and make me feel like screaming 
So any tips on how to deal with other children breaching boundaries in your house? My SIL will be here with them, which makes it more difficult to step in.
TIA