Hi @jacq,
Can you elaborate a bit on what you are trying to do?
If your goal is to clip all feature classes with the same land parcel polygons I would recommend using the 'Clipper' transformer instead (you can send all feature classes to the same 'Clippee' input port + there is an option to transfer the attributes of the 'Clipper' (the landparcel polygons in your case).)
@jacq I think I'd avoid trying to build a custom transformer with looping. Looping with blocking transformers can be tricky.
I think I'd try cloning your primary polygons (SP_PARCEL) and then grouping each clone with the various View Shed polygons. If you make sure your SP_PARCEL polygons are read first, you'll also be able to use Areas First on the AreaOnAreaOverlayer which will speed things up. You might also be able to make use of parallel processing options on the AreaOnareaOverlayer. I've attached an example workspace:
FME 2018Workspace: areaonareaoverlayer.fmwt
You should be able to use fanout for the output files.
Thankyou very much for your help, the clipper has given me the result I wanted.