So essentially the lines are the boundary of this polygon. I have tried spatial relator which only sometimes gives me a 1 to many join on every other line, I tried neighborfinder but I can get the attributes to copy over. I have specified merged attributes but it doesn't seem to be working. Not sure what I am doing wrong and help will be appreciated. The images show what I would like to achieve in FME. 
Question
I have looked at multiple spatial joining transformers and I am trying to create a 1 to many join by using a line feature I derived from a polygon. This line feature needs to take the same adjacent polygon attribute so 2 values need to be in the outp
+6- Contributor
+64
I would use the NeighbourFinder. You might need to switch the inputs to get the results you need. You can use the GeometryExtractor and GeometryReplacer to temporary store the geometry in an attribute and restore it afterwards.