We have removed the "combination" classes, with a much needed improvement in how the different classes work with pipe sizing.
Now, you can set up your Lateral type 1 as Schedule 40 for the smaller sizes, and set your Lateral type 2 as Class 315 for the larger sizes.
The system will automatically move pipe to the appropriate layer when it sizes. So now you can have more control with which classes are used, and at what size the transition happens. And of course you can also now get exact quantities by class of pipe.
The only thing to be aware of, is to set up your classes from smallest to largest. So in your example, your Schedule 40 for type 1 should have 1.5" as its largest pipe, and Class 315 for your type 2 needs to have 2" as its smallest pipe.
We should have the documentation on this updated later today, but certainly no later than the end of the week, all accessible from the "More info" link in the dialog.
--J