Mutable Extrapolation/Interpolation?

I am interested in having mutable interpolation types. I have a parent interpolation that I slice into and create sub-interpolations. See my package [InterpolatedRejectionSampling.jl](https://github.com/m-wells/InterpolatedRejectionSampling.jl) for context. Having a way to update part of an interpolation type in place might help with performance. Is there a way to do this without having to create a ton of `mutable` versions of all the required types from the ground up? Perhaps a couple of wrappers around the Interpolation/Extrapolation types?