Append line text to text of Tiddler whose name is constructed from a macro

[MagoArcade]

Hi all. I'm trying to append a line of text to a tiddler whose name is constructed via a macro. Consider abridged code:

\define MapLine()
{ "$(tmapid)$": { "x": 0, "y": 0 } }
\end


\define ViewPath(viewname)
$:/plugins/felixhayashi/tiddlymap/graph/views/$viewname$/map
\end


....


<!-- TIDDLYMAP VIEW -->


<$select class="tw-edit-texteditor myTextEdit"
        tiddler=<<$:/_opTaskStore>>
        field="TiddlyMapView"
        default="Default" >
      <$list filter=<<tmap "option" "selector.allViewsByLabel">> >
        <option value={{!!title}}>
          <$view tiddler={{!!title}} field="title" />
        </option>
      </$list>
</$select>


View path: <<ViewPath {{!!TiddlyMapView}}>>

The "View path" output is a bit mixed - it presents:

$:/plugins/felixhayashi/tiddlymap/graph/views/Live View/map

What I want to do is add text generated by the macro MapLine (which works) to the end of the text on the above tiddler - how do I do this?

Thanks