Really? Clear this up for me, let's say people are milling about at a kh and husband & wife are having conversation with someone, the husband is supposed to refer to his wife as sister so & so? how weird is that?!
At the kh they are brother & sister in jah I am presuming? it ends when they leave the kh? then they are back to being husband & wife?
As for kids calling non family members aunt & uncle that is common and a way to be respectful. We had a few friends of the family and we did the same. They were close to us and it would have been odd to call them Mr. & Mrs like the neighbor down the street. (naturally all non jw folks involved here)