How to restrict ways between two nodes? (e.g. rails between two train stations)

Hi,
I want to restrict my search on Overpass Turbo to ways between 2 train stations. I have the UIC reference of the two stations, now I am only interested about the rails that connect the two stations.
So I first look for the relations between the two stations, but that already gives me all relations of both stations. So I first like to restrict to only the relations going through both of these 2 train stations.
Next I want only the ways along these relations between the two train stations.

Here is my code so far:

[out:json][timeout:25];      
{{geocodeArea:Zurich}}->.searchArea;      
(        
  node[uicref=8503011]["railway"="station"];    
  node[uicref=8503000]["railway"="station"];    
  rel(bn);       
  way(r)(area.searchArea);   
);     
out body;    
>;         
out skel qt;