Hello
Here are a few pictures of the drain modifications of the rear kitchen sink, as the factory installation has the rear kitchen drained into the black tank
I changed the rear kitchen too either drain into the black or the grey tank
img 0022 shows a picture of the new rear kitchen drain pipe connected to the grey tank on the right and you can see the water tank on the left
img 0024 shows to drain pipe as it comes from the rear kitchen through a frame member by the grey tank
img 0028 shows the air vent added just by the rear kitchen sink , helps
img 0030 shows the 2 shut off valves one directs the rear kitchen drain to the black tank the other one directs the drain to the grey tank
img 0027 shows some of the plumbing for the sink
if there are any more pics you would like to see please let me know