Updating total field on master form with sum of values on sub form

[nonlinearly]

I get it. I think.
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2. If you do insist, then you have to have an event to update the value. It could be in the AfterUpdate of the Subform, where you could set the value of the control in the parent form to the sum on your subform.

No... people don't do that...
If the parent form is a bound form (as in our case) then if you press the escape key then the changes in the bound field of the parent's form will return to the previous value!!!
You must use after this: Me.Dirty=False