Disciplining other people's kids

My SIL has a much more gentle touch with her kids than I do. Yesterday I watched her 2yo daughter (my niece), let's call her Violet. Violet and I were in a store with my daughter, and Violet ran away and started giggling. I tried to say, "Violet, we can't play chase, come back here" but before I could even get it out of my mouth she was pretty much out of earshot.I raised my voice and tried to keep a firm/stern but not angry tone, and said, "Violet!" and counted to 3. She kept running away and laughing so I picked her up and carried her out of the store. Once she realized I wasn't playing along and that she was in trouble she started bawling.I feel really badly about upsetting her but at the same time what she did was really dangerous! If she had gone in the other direction and run out of the store she would have run onto a very busy street and instantly been killed.My SIL was okay with everything when I told her about it but I know her preference is to use a more gentle touch. She said that if she had been there she would have just played chase with Violet until she was tired out and ready to be done with the game.So I guess my larger question is, should I adapt my discipline strategy to be close to the parent of the child I'm watching? Or is it ok to discipline more harshly than their parents when they're in your care? I'm kind of worried that my niece is going to see me as the mean aunt now and won't want to come over and play with my kids since I am so much stricter than her parents. via /r/Parenting http://ift.tt/2pk4NjG