If you want it to appear in the drop-downs you also need to give it a category, subcategory (optional) and a name in the person properties xml.
<!-- Player club team type -->
<record>
<integer id="id" value="PtmT" />
<integer id="width" value="90" />
<flags id="customisation_context" value="play" />
<translation id="category" type="use" value="User Added" />
<translation id="subcategory" type="use" value="Optional subcategory" />
<translation id="name" type="use" value="Team Squad" />
<record id="widget_info">
<symbol id="class" value="team_type_label" />
</record>
<record id="column_widget_properties">
<flags id="alignment" value="left,centre_y" />
</record>
<record id="column_heading">
<flags id="alignment" value="left,centre_y" />
<translation id="text" translation_id="319549" type="use" value="Squad[COMMENT: column header text on a screen which lists recent international involvement for a club's players]" />
<translation id="hint" translation_id="319549" type="use" value="Squad[COMMENT: column header text on a screen which lists recent international involvement for a club's players]" />
</record>
</record>
This should let@hrmantovaniadd it to existing views.