How do you tell a family member they are selfish and ungreatful?

Question

My fiance and I are getting married soon as well as my twin sister and her fiance. Because our mother passed away when we were 17 and our father is MIA our Aunt and Uncle is paying for the wedding. My sister was kinda pushed into it. She wa not even ready yet but our Aunt said it is both now or you have to worry about it later (that is what was told to my sister). Now my sister always complains when our aunt asks us to do stuff for her and doesnt even want to get her a gift for doing all this. How do I tell her how selfish and ungreatful she is. She should have said no when she was told do it now...Let me have my day of glory alone. Am i being selfish. I do anything my aunt asks me because I feel she is doing so much..

Answer 1

Personally I would just tell her straight with a few examples of recent ingratitude and selfishness, it may be that she doesn't realise how bad she's acting or she may be doing it because she is unhappy with the situation.  Remind her that she did have a choice and she made the decision.

Answer 2

just  tell here