My fiance has a niece who really wants to sing at the wedding. The problem is she doesn't sing well... at all. Still because I know its important to her and she is important to my fiance (he helped raise her because her parents had issues), I wanted to let her sing a song as the guest were arriving, like one song. When I asked her what she had in mind, she had a whole set planned, and most of them are songs that she could not pull off well, like a lot of radio songs with auto tune. So how do I politely pick a song for her and tell her no more than one? The thing is, the poor dear doesn't know she can't sing, her family has built her up to believe she could be a famous singer one day. Just to clarify, I'm not being mean to a child, she's 18 years old, but very much the princess of the family. Any good advice?