I went to fileden and apparently you have to have a phone and every thing on the planet to register and I don't have a phone of my own. I don't know why this forum just don't let people upload files.
No that is a crap advertisement. You don't need anything. There is a skip some place on the page. But I just hit back button on my browser and it works. The thing I don't care for about media fire and other sites is the sit and wait to download. Fileden doesn't plague you with waiting or ads on download. In fact it is a harder to wade through the ads to upload than it is for people to download. I want people to download my files without issue and that is why I use it.
Sorry about not warning you about the crap ads at start up.
Ok I took a look at what you are talking about and could see a way of "cheating" by adding an invisible plane above the visible plane but this would not be true accurate physics. Also I assume what you mean by effecting the environment would be the rotating child to go tumbling off to the right since it has the rotation. But this would violate the parent/child relationship. I guess the next thing to consider in this puzzle you have presented is; why do they need the parent/child relationship in the first place?
For example; The child on the left could be remove from it's parent and switched from static to ridged body to have both effect on the other objects and plane below. However as long as it is constrained by the parent cube the link will follow.