I removed the transaxle inspection plug and the fluid is just a little low, so I was going to top it up. Can I do this from the inspection hole or should I do it through the transfer case fill hole?
if you replace thru the x-fer case fill hole, leave the inspection hole unplugged on the diff. until fluid drips out. leave things sit for a few minutes and then re-check for too much or too little. i'd changed my 328 many times in this manner. i believe this is Ferrari's accepted procedure.
You can add a bit through the inspection hole. It probably won't take but 2 or 3 squirts from a quart style oil pump.
Never seen the top plug used for filling in a professional environment in over 40 years. With car level put a pint in the top plug and fill in the rear plug until it overflows.......done. Lets not overthink this.