Utilizing the LinkToMarkedPoint and the LinkSlopesBetweenPoints subassemblies you could achieve this effect. Those can be found on the Generic tab of the of the Subassembly Tool Palette. How that would set up would depend on which portion of the section would be allowed to vary, but essentially you would target your surface and place a marked point at your daylight. Then either come back from that point one meter and place another marked point and target that. Again, all of this would depend on which portion of your section would be allowed to deviate. Does the one-meter portion vary in and out? Or does the slope deviate from the defined 1.5:1 slope? There are several videos on how to utilize and target these subassemblies in your assembly. I hope that this helps!
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