Feature request: curve composition

Suppose I have a non-default velocity curve for my keyboard (default is linear [0, 127; 0, 127]). If a preset have default curve, I can just load my curve and play. But some presets have custom velocity curve (for example, D4 Blues) and can't see easy way to apply the curve to my keyboard.

So, my request is ability of make composition of current curve with another curve.