Here’s how to enable a checkbox to be updated enmasse. First create a new extvardef.php file containing the following:

OPPS - somthings gone wrong. There should be something else here, but it isn’t. Sorry!

Then put that file into at the following location

/var/www/html/custom/Extension/modules/ Module_Name/Ext/Vardefs/

Of course, you’d want to check any existing files in the folder to make sure none of them already deal with that field.