I need to add a new field to the Edit In List. That's not a problem. The problem is that at a form level the field is mandatory on the relevant detail form and to provide consistency I need to make it mandatory on the list form as well. I dabbled in WSP by setting required = yes, but that didn't work for me.
In the list form I have the following specified for the field...
<PDM_MACRO name=lsCol hdr="Affected CI" attr=affected_resource.name>
This allows the CI to be available and update able but not mandatory.