Two "ceremonies" -- One Dress

The civil ceremony and reception of my wedding will be in Portugal in June (almost Summer) and the party (with a "simulated" ceremony) with my family in Brazil in August (Winter). I have a full-lenght sleeveless champagne dress + a full-lenght (French-sleeved) organza dress over it. They are independent pieces. I would like to look authentic at both places without wearing exactly the same thing as I cannot afford to buy a second dress. Any ideas about complementing the sleeveless dress for Brazil? Any suggestions would be appreciated.