Hi Jennifer,
The special effects team would render the final results back in DPX format so it not possible to reference back to the original RED r3d files, unless the special effects team use the original RED r3d files instead and then render the final results to DPX format for you to grade in Resolve.
On a side node, you may want the special effects team to give you the mattes that they have created so that you can use them for isolation in Resolve. If a shot has different mattes, you can ask them to put them in a single DPX file as Resolve now supports different mattes in the DPX RGB channels.
-chrispy