Constraints of Grease pencil on layers and (+material,Vertx Group level )

i would love be able to add any Constraints on one single layer or a bunch of layers or materials , as example, to use follow path constraint on a layer to make a chararacter do a 'jump' so the jump path is the curve and we can easely tweak the curve path. (same principle as bone Constraints)

Also we must remark that interpolation will be done in one place within the layer so no offset is needed. this will open many possibilities and not break the workflow of how we plan to create something or in the middle of the creation... hope to see this in GP 3.0