For sure - my girls stay at my mum's and MIL's overnight without us and if they did something they shouldn't then I would expect them to be disciplined. Also my mum looks after the girls one day a week while I am at work so it wouldn't be right if she couldn't do that.

If I was at someone's house and my girls did something that wasn't acceptable in their house then I would expect that person to say something to them. There are things we do at home that other people don't and the girls need to know that sometimes different rules apply so I wouldn't have a problem with that either.

As far as smacking goes, we don't do it, my parents and IL's don't do it and I wouldn't expect anyone else to do it to my child.