How to exclude shared edge for TrimExtend Builder ?

I'm working on creating Journal for TrimExtendBuilder.
Suppose there is a body shown as below diagram.I want to extend its perimeter outward by 10mm.

When I launch TrimExtend command interactively, system let user select only perimeter edges ("OOOOO" and "O--M--O" in the diagram). So, we don't select shared edge ("MMMM") in the middle of the body.

O--M--O
O--M--O
O--M--O
O--M--O

I wrote journal below for TrimExtend Builder, But,the for each loop detects all edges including shared edge,"MMMM". As a result, I got error during TrimExtend Builder. I want to exclude the middle edge as interactive mode does. How can I do this (excluding middle edge) in journal?

''' Journal ''''
Dim MyBody as Featers.Body
For each TempEdge as Edge in MyBody
' Do TrimExtend Builder with selected edges
Next

Thank in advance,
Kazu

Try recording a journal of performing a trim/extend while using the "sheet edges" curve rule. You should be able to use the same curve rule in your own code.