Unrelated to your question but I think there might be an error hidden in your Road slope pkt file with how the slope transitions when the swale is detected. Take a look at when the swale elevation is set to -2 and the surface elevation is set to various values above and below that value. The swale bottom is showing up before there is a surface to daylight to, also you will want there to be a smooth transition with the Slope 2 otherwise your corridor will have weird bumps.



Related to your question, I think the only way you will be able to give slope 2 to slope 1 would be to include the top surface of the road (along with those targets and applicable input parameters) as auxiliary points and auxiliary links in your road slope pkt file and to attach that subassembly to your assembly in Civil 3D first and then to add your road as a second subassembly that can then reference the slope 2 as a parameter reference.
Kati Mercier, P.E. | LinkedIn | AutoCAD Civil 3D Certified Professional
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AU2019 Speaker::: CES321590: Analyze and Revise Existing Subassembly Composer PKT Files for AutoCAD Civil 3D
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