form widget question

[Christopher Snow]

I have a field that is returned in a form list:

<field name="riskOwnerPartyId" title="${uiLabelMap.Owner}">
   <display-entity entity-name="Party" key-field-name="partyId"/>
</field>

I would like to display "Party.lastName, Party.firstName" and not the
partyId.  

How can I do this?

Many thanks ...