I’d be careful and double check the levels of the transfer case a few times after a refill. With a cooler in the circuit it will be hard to know for certain the true level unless you measured exactly what you took out and put the same back in.
For example, would draining a cold transfer case produce less/more fluid than a hot one? What cooling cycle/mode was the transfer case in when drained? Does that even matter? Is the fill plug even a legitimate measurement point for the transfer case like on a differential or does the manual call for putting in a specified amount which has no relationship to the fill port?
I would have to think there is a specific drain/refill procedure the dealer performs which involves hooking their diagnostic system up to the vehicle and triggering a circulation pump, assuming it’s an electrical one. Would love to see Ineos service documents on this procedure anyone have a friend at a dealership who can take a screen capture of their software?