Select which vertecies bind the mesh in MeshDeform modifier

On the image below is the MeshDeform modifier. Shocking, I know. What I want is to have another Vertex Group input window, that allows me to decide what vertecies are "bindable".

The situation: I have three low poly planes in a single object. After cloth sim works it's magic with self collisions on, I add modifiers on top so the lowploy can bind to the high res models. (low poly) (high res :O).

The problem: I can't choose which lowpoly plane binds to which high res plane, that leads to an ugly result after the modifiers. It's a sisyphus task to align all the planes as separate objects with the cloth sim and collisions, so they perfectly fit together while taking the modifiers into account. At least I can't do that.

This also just seems like a good idea to me, opening up a lot of things with one simple option.