Its likely not worth the effort.
You need something (a mesh specifically built to allow it) that allows this kind of behaviour:
If you do it, then you can just use vector fields to displace whatever you want in ehatever shape you want…
Since its based on vectorfields you can even do heavy animated displacement at no extra cost…
(I really should package this up for the marketplace…)
Of note, this would allow infinite levels of interaction. You just render stuff to a vectorfield RT and the grass automagically animates… easy peasy…