Hi, I am currently trying to achieve a “crumbling floor” effect for a little VR experience in Unreal Engine 4, but have a few difficulites figuring out how to best go about it and hope someone here can help me. I am still learning houdini, but feel like I am not to far away from a decent result this time

My idea is that I have a rectangular shaped floor which overtime “loses” floor tiles in circular fashion along the boundaries.

I have setup a circular color gradient on my floor geometry and based on that color I move individual faces upwards with a keyframed animation.
This all seems to work fine. But as soon as I try to use the RBD fractured Object shelf tabs I get stuck or maybe what I am thinking about doing is not even possible the way I have it setup?

What I would like to happen is for all white pieces to be affected by a gravity force, while all other pieces remain static.
Is there a way to keep adding the generated white tiles to a dynamics group which than affects them as soon as they are being generated?

Since its hard to explain what I mean exactly here [imgur.com] are some pictures and my file.

At the moment I have a mask object to prevent the middle part of the floor from being affected, but this seems more like a workaround rather than a solution.

Any help or ideas, also on how I would get something like that into unreal engine would be greatly appreciated