This isn’t going to work in an Add screen because Add screens are not attached to to any rows and don’t have a parent row to pass values from. It also won’t work in a Form screen because no row has been written yet and you can’t change any data on the parent row while in a form.
I think this would require two checkboxes, pointing to the same column, with different titles and visibility conditions to show each checkbox based on ‘true’ or ‘not true’.