Fabienne - I would ask specifically if your son is invited. People (OK - my mother-in-law) told my wife and I that we shouldn't allow children at our wedding, but my I consider my friend's children to be a big part of who they are - and I insisted that the children be allowed to attend. Maybe it's just because I like kids, but I love it at weddings when the little kids are all out on the dance floor - and I've seen some really cute scenes where the bride and bridesmaids are dancing with multiple children. As to the shawl - I see no reason why white can't be used as an accent color. It just shouldn't be the main theme of your outfit.