The right low beam should be on fuse # 10.
The fog lights should be fuse #1
Don't be tempted to put a higher rated fuse in the holder. See the thread "my sedan is dead"
I would start by dividing the system in half, or sections.
Disconnect connector "A" in the figure, at the ARC. It has been a long time since I've been into a Milano/75. I don't remember how hard it is to get behind.
But if you can separate the circuit there you will now know if the short is before the ARC or in/after the ARC.
If fuse blows, short is between the fuse and the connector "A"
If fuse holds with this disconnected, disconnect "C" and "F".
Reconnect "A", if fuse blows, short is in ARC.
If fuse holds, connect "C". If fuse blows, short is in wiring to Right Rear light.
Separate that into sections, Disconnect G73a (right rear light connector) or unplug rear light assembly.......... repeat for each section.
If fuse holds, Connect "F".
Disconnect the front left light connector(s) repeat above steps
You can connect a lamp across the open fuse holder contacts, or get a box of fuses.
The inverse law of fuses on hand determines how fast you will isolate the problem. Lots of fuses on hand and you will find the problem in short order, haha. Only one fuse on hand and it will immediately fail. And each time you return from the store with less than the critical number of fuses, you will always need one more.
Doing it this way in just a few steps you should be able to isolate which section of the car the short is in and then you can take just that section of car apart rather than starting at one end and working your way through the whole car to the other end to find the problem.
good luck,
Wayne