A question I get asked most often is, “What songs will you be doing for the wedding ceremony?”
A church wedding is different than a wedding ceremony (off-site location).
In a church wedding (assuming it’s a Catholic Church), all the songs will be mostly from the Flor Y Canto book. The processional, mass and recessional songs would come from this book. The choir/musical director of the church can best assist the mariachi band in the most traditional songs for the entrance/exit. Some churches may not let you play any secular music (i.e., “Motivos” “Somos Novios”) inside the church but will allow it outside as you exit.
At an off-site wedding, with a wedding officiant, it is more common to hear songs like “Solamente Una Vez” “Motivos” “Hermoso Cariño” and most of the romantic traditional mariachi songs.