I am not sure but VBAPI is having least functionality.
You can try below on Drawing file with Pro-Toolkit:
- collect all symbol instance having name as weld type
- Collect leaders associated with symbol (ProDtlsyminstdataLeadersCollect)
- Get attachment of All leaders (ProDtlattachGet)
-Get model item of attachment (ProSelectionModelitemGet)
-Get surface from Geomitem (ProGeomitemToSurface)
I have not tried this but it should work.
Regards
Ketan