I have two connections. The front connection is Black #1 and Grays #1 and #2. The second connection is for the 1/2 bath, Black #2 by the rear steps about 20' away. I thought about connecting them with a pipe but getting around the axles and such I was concerned about clearance issues, appearance and proper drainage. My solution was to modify the length of hose at the CG connection (90 deg. elbow) to about 2', put my "y" and then run to the sewer connections on the trailer. Each run of hose is supported by sidewinders to drain properly. What I'd like to find is a "Y" elbow so it "y" right at the CG's sewer connection.
I've seen a "Y" elbow that connects to the CG's sewer pipe at a CG but the owner was not around to ask. Have not found one online or in a store.