Controlling a bones animation

Is there any way to limit a single bone’s ability to follow an animation via a 0-1 scale?

An example is if I have a breast size slider, 0-1(Float) and the animation contain movement for the breast. With a breast size of zero, it wouldn’t make sense to have it following the animation, so is there a way to simply lower the vertices ability to follow the bone based on the breast’s size?

I should note, I want to do this for several bones(For instance breast.L, breast.R, and butt.L or whatever) and would prefer not to have separate animations for 0 & 1 then blend between them.

I am hoping this is in the right area and such. I have tried to find data on this, but nothing I have searched or looked for has brought anything close to an answer.

Thank you.