Hello GefM,
We've never been invited formally to a wedding but while sitting at a restaurant/bar, a Cuban gentleman asked us if we could take photos (we had a polaroid camera with us) of the bride and groom since there were no photographers at the wedding.
Needless, to say after many photos ..we were now part of the wedding party...had a great time meeting them.
We did bring a gift to some of our Cuban friends who got married (we couldn't attend).Would you believe they love "Tiffany style lamps" for their new home?Yes, we got it there in one piece ..yes, we were checked (the wires in the lamp were a give away).
Anyway, that was our experience with weddings in Cuba.
Hope you can attend and have a great time.
:)