System families are built in to Revit. You can use them in their built-in state as is. There is no need to add them to your add-in, because they are already contained in and provided by Revit.
System families are built in to Revit. You can use them in their built-in state as is. There is no need to add them to your add-in, because they are already contained in and provided by Revit.