If I'm understanding how this is set up, Dave pulls the info from the user's plant list. If the only line under the individual's list status is "have" or "prev", it shows on the availability report as status "BLANK FIELD". Else it shows trade or sell (and the particular plant part being traded or sold). That's a programming function, not a user function.
IF "have" or "prev" is the only line on the individual list status, THEN the report could automagically read "Not for Sale or Trade" or "Inventory" or "Unavailable" rather than a blank. User's wouldn't have to do anything extra - just like no one does anything extra to make the status field blank in the availability report.
It would be for Dave to decide whether a default message in the availability report's status field is useful. IMO it would clarify - but as I mentioned I'm always nervous when I see blank fields..
Does that make sense?