Interp Function

Hi guys

I have 2 sets of data kz.b and kc and the refence variable z.b

currently i can interpolation to find what kc is when z.b is equal to a value hence the below;

however there a various values of Kcphi which i may need to interpolate between such as if

kcphi was 6 i would then need to interpolate the value between kcphi5 and kcphi10 to then return the value and interpolate z.b to return the vlaue i am after.

i was wondering if there is a function that could be written to help with this

Thanks 🙂