Ordinarily, the Church encourages that songs performed during a public liturgy be religious songs, as is fitting for the solemn religious nature of the event. Indeed, even some religious songs may be discouraged in some parishes if the lyrics may be in tension with Catholic doctrine (e.g., “Amazing Grace,” “Mary, Did You Know?”).
If the song you want your friend to sing is secular in nature, I recommend that you ask her to sing it at your reception. If the song is religious in nature, I recommend taking a copy of the lyrics to the wedding coordinator at the parish where your wedding ceremony will be celebrated and asking that person if the song is appropriate for the nuptial liturgy. If the answer is no, I recommend asking your friend to sing the song at the reception.
