Customer Management - Calculations when unchecking and checking multiple invoices at the same time

Scenario - User both checks and unchecks the uncollectible check box and Saves
Calculation should add back the original Balance for the invoices that are unchecked and subtract the balance on the invoices that are checked.

00442/JAT/Waterford Crystal
4 invoices - Balance total = $54.78
Check invoices 7998 and 7997
Save
Balance becomes $48.23
Page refreshes
Uncheck these 2 - 7998 and 7997 while checking 7996
click Save

DEFECT-
Balance becomes - $54.78 as if the newly checked is not recognized

Fix so a Update will both perform the check and uncheck task when necessary