Qualatex magazine "Images" Nov/Dec 1994 issue page 14 has a recipe for making the bride & groom. It is a smaller version than what I am assuming you want but it is a good start. I would just modify the instructions to use larger balloons since you want this to float. I wouldn't use anything smaller than an 11" balloon downsized to maybe 9" or 10" in a cluster of 5 or 6 balloons. All depends on how tall and wide you want this to be.
I also saw the Prosper video and I have to tell you I used to be a professional clown and went to a balloon class he gave that I thought was for making balloon animals. It turned out that it was for balloon decorating and that class made me decide that I LOVED balloon decorating.
Good Luck!
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Instructions for a Bride and Groom Sculpture by: Margit
Hi Alfreda,
I suppose you want to make a sculpture with round balloons, not one with twisting balloons. I would recommend to use air filled balloons as they have a much longer life time than helium filled balloons. I don't have instructions for a bride and groom sculpture myself, but you could check out this 'bride and groom recipe' at BalloonHQ. Unfortunately, there are no pictures to illustrate the instructions.
The following video shows how to create a bride and groom. Even if it's not exactly the design you had in mind, you might get some good tips out of it.