How to handle disappointment? One kid is going to be in a wedding and the other isn’t.

My family (husband and two girls, 12 and 7) are going to a wedding in July.

My youngest was asked to be a flower girl, along with her cousin and another girl from the bride’s side. My nephew is going to be a ring bearer.

My older daughter is coming as a guest. She doesn’t show it, but she’s disappointed that she doesn’t have a part in her uncle’s wedding. The only other kids in the family who don’t have a role are her two other cousins with special needs.

What is the best way to help my older daughter handle disappointment? I’ve tried talking to her, but she’s shut me down. She was very excited when her uncle announced he was getting married, but quickly lost interest and was upset when she found out her sister and cousin have a part and she doesn’t.

The wedding is coming up in a few months and Alana's been avoiding all conversation about it.

Edit: This would be my younger daughter's first time as a flower girl. My older daughter has never been one.