Basic Idea is of a rich family that lives together in the house:
Fraternal Twins (Boy and Girl)
And well...they all participate in Incest together.
I would be playing the part of the male half of the fraternal twins.
Soo...anyone..interested? o-o We could come up with a plot if you like..perhaps the every day life of the family, or perhaps they are getting ready for, and go on, a family Vacation together to a nude beach or some such.