Dishwasher flex drain to black hose quite a distance from sink
I'm replacing the builder's ge dishwasher with a stainless steel LG dishwasher. I removed the GE and there is a flexible drain hose that I took off it. The dishwasher is on a wall perpendicular to the sink wall. The flexible drain hose runs into a hole in the back of the cabinet next to the dishwasher. From that point the hose or hoses are not visible, go around a corner, through the bottom of another cabinet and then appear under the sink base cabinet as a black rubber hose that then is attached to the sink drain through a T fitting. The GE hose connects in some hidden spot to this black rubber hose.
The LG hose is attached to the dishwasher, underneath, hidden behind a plate. The end of this flex line has adjustable sizes of 1", 3/4", and 5/8", you cut it off to suit.
Do I need to couple the two flexible drain hoses, or do I figure out how to remove the GE hose and connect the LG hose to the black rubber hose? If so, do I pull on the GE hose and push on the black rubber hose under the sink until I see the connection, or do I pull on the black rubber hose until I see the GE hose and then disconnect that, and attach the LG. I'm afraid I won't be able to snake the new hose back around that corner to where the dishwasher opening is in the cabinetry. Any suggestion greatly appreciated.