You may notice that when you use bulk edit on Contacts, the Parent Customer field is disabled, not allowing you to assign an Account to a group of Contacts.

 
You can enable this field, to allow editing by doing the following:
1)      Export the Contact entity xml
2)      Edit the XML
a.      Search for “Parent Customer” or whatever you have named that field
b.      Find the following line
<event name="setadditionalparams" application="true" active="true">
c.      Set the ‘BehaviorInBulkEditForm’ attribute
<event name="setadditionalparams" application="true" active="true" BehaviorInBulkEditForm="EnabledButNoRender">
3)      Import the XML and publish
 
You should now be able to edit the Parent Customer field when bulk-editing Contacts.
 
The following options can be used:
  • Disabled – does not allow editing
  • Enabled – allows editing of the field
  • EnabledButNoRender – allows editing of the field, but does not fire OnChange events associated with the field.