I think, in most cases, parents trump aunts/uncles/grandparents, but if the parents aren't parenting and overriding house rules when visiting it is problematic. Example, when we go to my parents house, my kids, who are pretty well behaved, always liked to play with Grandmas' statues and figurines she has dotted here and there. I wasn't in the room but heard my dad tell my then 3 yr old DD she wasn't allowed to touch, just look. I did not override my dad's rule because it was his house, his possessions and he had the right to say that could not be played with. If OP says no running in the house and no unsupervised kids on that high of a balcony, then the parents, as a visitor, should also enforce that rule. Just because you let your kids run in your house or climb on furniture, does not mean that everyone wants that in their house. OP, if you choose to keep hosting, I would go into broken record mode until they either follow YOUR house rules or they quit coming because their kids should never be told no.