What about making this as a part and then splitting it into smaller parts and making an assembly? That allows you to make the fillets in a single file.
Create the basic shape you are after.
Apply your basic fillets
Cut in a partial fillet as you've done before
Cut revolve as you did before to finish off the partial fillet.
I'd convert the sketch from the step above so the two sizes are always related.
Repeat the two above steps for the other edge. In this case, start with a derived sketch so everything is the same and stays linked to the first partial fillet sketch
Sketch a line and use the Split command to split the model into two pieces.
Model in your third piece, but choose not to merge it with the others when extruding.
Use the Save Bodies command to rename and save each body off as a separate part. You can also have the software create an assembly at this point, and apply different names to the new parts.
The final assembly. Each piece will show up in the BOM as you desired.