My brother has a son who is 2 1/2 years old (also my ringbearer). My nephew lives with his mother (who is no longer with my brother). Her 20 year old son also lives there. They are all invited to the wedding. How would I address this invitation? I am assuming because my nephew lives with her he should be on her invite, not my brothers? Should the 20 year old son then get his own invitation? And I will also be inviting them with guests.