Just to clarify... I did find what was causing the vert itself to get added and fixed that.  As for the complete list of neighbor verts, I also found a potential problem with that (my fix needs testing), but what I'm doing internally is...

• get list of vertex Ngon neighbors ( vngons = mesh.GetVertNgons() ) and then...
• walk through the list of ngons each vert is a part of and building a list of (unique) vertices used by any/all of those ngons (now properly excluding the vertex itself).

...so just to clarify, my code doesn't know anything about any potential screening you might be doing, before or afterwards.

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