If it were me I'd be telling them straight off to get stuffed lol, that's just rude. Geez, I'd hate to hear what they would say if you were to run away and get married somewhere, then have a party back home with family and friends to show them the video of you getting married.
Like everyone has said, it's your wedding, not theirs. Besides, there is no book saying exactly how you "have" to have a wedding.