Dragging bar updates tabel
 

Older versions of excel had a feature that let you click on the end of a bar
and drag it. The new length automatically was updated in the data table. I
have replicated it by writing macros with buttons, where the click identifies
the data element on the chart and the button with a directional arrow
increases or decreases the associated value in the table, but the old touch
the graph and move the bar/data was much easier.