Spline graphs

Two similar spline calculating sheets. Graph with reference line scales overlaid with a scatter plot. Overlaid with a 5 point spline plot. The 5 pt data is entered manually and the calculated spline points put into a column. 88 data points for each key in a piano action design. Need this asap. Would also like to look into the potential of adding the ability to pull/drag the spline points as desired as well as manually entering