Hi Therax,
Love your mod!
I find the fact that copy-paste also includes your underground pipes actually quite irritating.
More often then not, I don't want the underground pipes copied or cut.
Is it possible to make this a mod setting? So people can choose themselves whether they want this to happen?

I will look into making this a toggle. For now, did you know that if you hold Shift while using the copy or cut tools, the standard blueprint creation dialog appears? You can then toggle off the “pipe (underground)” entities to remove them from the resulting blueprint.