What happens to your cut list when you add holes to your structural members? You can have structural members that are identical but if you add holes to these parts, SolidWorks will pull the component out that has the holes and make it a unique item. That's because it now is unique. Let's take a look.
Here we see a Weldment that has two different items. Side Rails and Front Rails.
The Side Rails are identical and the Front Rails are identical. Notice the Highlighted Cut List folder in the feature tree. SOLIDWORKS is looking at the Weldment Profile as well as the member lengths to determine the folder structure (it's only looking at the Profile and length because there are no other features that separate the members at this time.)
Let's see what happens when we add a couple of holes to the Front Rails. I added a couple of hole wizard holes to only one of the Front Rails and then you right click on the Cut List folder and select update. You now see that it pulled out the member that had no holes and created a new folder for that item. So now I have exactly what I would expect, two rails are the same and then two different rails, one with holes and one without. Same length and profile the only differences are the holes.
Hopes this helps clear up what is happening to your members when you add features to them. It will affect your Cut List because they are now different.
Computer Aided Technology, Inc.