Oh ok, now that clarifies a lot of things, sorry for the confusion

I doubt however that foreign families would be interested in exposing themselves through a photo-documentary, as unnecessary publicity is rather NOT recommended when living in China. Also you are starting from the principle that this policy is bad or "injust", while there were real motivations for the Chinese government to put it in place, and there may actually be advantages to it, that could be uncovered by a more in-depth study.
Wish you good luck, will talk about it to a couple of friends here who are already married (mixed couples mostly), and should they be interested they will get in touch with you through PM.