Form with input that allows user input but also has initial value controlled by enum

[leonsteber]

Hello good people.

I have a form with an input that shows a rainwater tank's last water level. The user can change this level but also has the option of setting it to FULL or EMPTY (an enum). 

See the video: https://drive.google.com/file/d/1H-vxKSYRlMmtBnbTG4gx8d-hckZCP8C3/view

The FULL and EMPTY works initially but as soon as the user manually adjusts the value, the enum FULL and EMPTY no longer works.

I've tried playing around with the Reset on Edit but can't get it to work. 

Is it possible to have the enum FULL / EMPTY change the value at any time regardless of whether the user has modified the water level?

EDIT 1: There are several different tanks so FULL and EMPTY values change with each tank. Can't use RANGE, as I can't change min/max and when I'm working with max values like 3645mm.  I've already set VALID if so user can't set value outside of the FULL/EMPTY.

EDIT 2: The reason for having EMPTY and FULL is so that the user, when out in the field, about to pump water to a tank, can quickly show if that tank is FULL or EMPTY. I have several tanks and the values change for each, for instance FULL may not always be 0mm from the top of the tank, it may be 30mm.