hi, I have a friend whose sister (baptized Catholic) is going to be married to a boy (not Christian) with whom she has been living with (fornication) for 3 years. The wedding is going to be done by a "friend" of the groom, so its not even a Christian wedding, its more of just a civil union/marriage. My family was invited to this wedding. As devout Catholics, should we attend? Will their "marriage" be recognized by the Church? What message would our attendance (as faithful Catholics) say about our view on them living in a state of mortal sin for several years? Should we just politely decline the invitation? I don't know what to do. Please help.