Set values from one list (for pipe fittings) into another list (for pipes)

Hello community!

I’m fairly new in the Dynamo world, and I hope someone can help me.
I have a plumbing model in Revit. I added a new parameter for Pipe Fittings to apply a key number for some of these fittings (3, 4, 5,…). The Pipes between these key points have a parameter to identify which points it is between (3-4, 4-5, 5-6,…), that I filled by writting (it’s not automatic).
In Dynamo, I managed to get the elevation of each key-fitting. For the pipes, I managed to split the list of “sections” to identify which key points (fittings) are involved (segment 3-4 have key 3 and 4, …)
Now what I want to do is get the elevation for key-fitting X and apply to a new pipe parameter called “Elevation End Point of the Section” and elevation of key-fitting Y and apply to another pipe parameter called “Elevation Initial Point of the Section” (for example, in pipe section 3-4, I want the elevation of key 4 as “Final Point” and key 3 as “Initial Point”).

Any help is appreciated!