TopoGeom_addElement — Adds an element to the definition of a TopoGeometry.
topogeometry TopoGeom_addElement(topogeometry tg, topoelement el);
Adds a TopoElement to the definition of a TopoGeometry object. Does not error out if the element is already part of the definition.
Availability: 2.3
-- Add edge 5 to TopoGeometry tg
UPDATE mylayer SET tg = TopoGeom_addElement(tg, '{5,2}');