My fiancé has two younger sisters, ages 17 and 10. I did not ask them to be bridesmaids, because I thought that they would be better fit to be involved in the wedding doing something else. His mother is very upset with me, and doesn't seem willing to sacrifice unless they are bridesmaids. I picked my best friends and my sister to be in the wedding party, simply because they are old enough and responsible enough to plan things and help celebrate. Is it wrong that I did not ask his sisters to be bridesmaids?