Using in-families lines to create lean concrete

Firstly, I’m using new Dynamo and Revit 2017. In my graph I used Category.Subcategory created by myself (copying from Clockwork in DynamoStudio, since I can’t add Clockwork package to list).

I want to use in-family added lines, filter those lines and use it to extrude lean concrete under the slab. Can you give me any hints, how to categorize those lines and use them to extrude? I can’t filter them out of the model.

I attached my graph and sample of family. The goal is to get lean concrete as the image shows.

chudy beton.dyn (8.6 KB)

sf model line dynamo.rfa (476 KB)