As Simple as this, You have a JavaScript which copies one field from to another using onchange event in the form, then remember JavaScript are triggered only when the form is opened or is being opened.
But what if you want to edit multiple records at once using the OOB grids, your code will not work. The fix is an 4.0 solution.
I term this as unsupported customization as I found in SDK that this should not be updated, but again similar kind of post MSDN EMEA which guides you how to do it.
To explain more:
The BehaviorInBulkEditForm attribute must be set to one of the following values:
- Enabled: The field is enabled and the OnChange code is executed.
- Disabled: The field is disabled and the OnChangeCode is not executed.
- EnabledButNoRender: The field is enabled, but the OnChange code is not executed.
This is what we need to do:
- Export the entity as a solution for which JavaScript needs to be enabled during Bulk Edit.
- Open the customization.xml
- Add BehaviorInBulkEditForm=”Enabled” to the event handlers where your function is called.

This worked even after multiple export and import of entity. Both for CRM 2011 and CRM 2013
Thanks!!!

