Here is a picture I took of my daughter last week. I grabbed my camera and starting shooting to capture the moment. There is only one overhead light in our kitchen and she is turned away from the light source. The result is shadows hiding what her most expressive feature is. Once I got a few quick shots taken care of, I decided to risk breaking off the moment by moving her.
All I did was swing her so she was facing towards the light and voila, I shot in which the viewer's eyes go straight to the subjects eyes. A nice perk, since she was better lit I got a crisper shot using the same settings.
Inside you don't have to worry about stunning your subject with too bright of a light. But when outside I wouldn't recommend making your subject look straight into the sun in order to get catch lights. Because chances are you'll just get very squinty eyes, not attractive. Try finding light that is diffused by trees, anything that softens the light without eliminating it.
Now I still say if the subject is a child and moving them will interfere with what was deemed photo worthy when you pulled your camera out, just shoot away and enjoy. But always keep the light source in mind and work with it.