The Add Part Grid configuration is defined as a Grid view, using the tags described in the application Help under XML Tag Reference - Grid specific. This article provides an example of an Add Part Grid with a default value pre-set for the parameter. 

Example Data 

Example Configuration

        <Parameter caption="Design arch" name="p1" hintContextPath="ITFD;ITAP;ITFC;ARPP">
                <ForEachPathReference path="ITFD;ITAP;ITFC;ARPP">
            <ItemNameColumn width="200"/>
	<ForEach select="$p1/IADT/IDLD">

Example Result