Are there any reasons to spank a child?
Your question is really more of does anyone have a reason to spank another person’s child. The answer is no. Your father should have brought your daughter to you for any discipline that was needed. The other issue is the intensity of the “spanking.” Unless your daughter bruises very easily, there should never be a bruise from a “spanking” of a four year old. Your daughter will be fine with encouragement and a little hug. Kids are very forgiving. I am more concerned with your father.
