Holiday amendments - being able to preview amendments before they are changed on the system.

We would like to be able to preview changes we make within the settings field of planner before they are made permanent. At the moment you make a change, and then save to see how it looks in the planner field and if it's not quite right, you are unable to overwrite what you have just done - if we could preview how the amendment looks it would save a lot of time and help the "This Year" history log to be much clearer.