Selection.Combine Method (Visio)
Creates a new shape by combining selected shapes.
Calling the Combine method is equivalent to clicking Combine in the Microsoft Visio user interface (click Operations in the Shape Design group on the Developer tab). The produced shape will be the topmost shape in its containing shape and will inherit the text and formatting of the first selected shape. The original shapes are deleted and no shapes are selected when the operation is complete.
The Combine method is similar to the Join method but differs in the following ways:
The Combine method produces a shape with one Geometry section for each original shape. The resulting shape will have holes in regions where the original shapes overlapped.
The Join method differs from Combine in that it will coalesce abutting line and curve segments in the original shapes into a single Geometry section in the resulting shape.