However, your daughter is very young and has not learned or had a need to fear the aliens. Perhaps she'll never have any fears where aliens are concerned. Your sister's idea of testing is only part of what aliens do. A very large part of their mission seems to be shaping people's attitudes about their world or to teach them about the consequences of not taking better care of the earth, etc. Being afraid of aliens is a learned behavior.
Fear is a learned behavior.
We are fascinated with what we perceive to be as their bravery. But it is not bravery at all. It is simply risk-taking behavior without ever having been hurt or suffering any consequences. In the case of your daughter, it sounds as if her contact has been positive. In other words, she may regard these beings as her secret playmates.