Neuse:
Well, Yes and/or (inclusive OR) No. I’ll be cautious. I have no idea what this “Sel Sw” is. What are it’s contacts rated for? A picture (Suitable Fo’ Framin’) of the front of this switch, and the back of the switch, is
necessary. For example, as connected, it
appears that a terminal (possible the Common or Output, who knows, it’s not labeled) is connected to the starter solenoid. The starter solenoid is mounted on the starter and draws only about 12A. The solenoid, when energized by the start switch, switches a large current (about 125A normally. But if the engine is frozen, or the propeller jammed, it can draw a hellacious amount more) from the battery(s) to the starter motor during the start. There is no wire size shown for this starter motor wire (supply red, return is through the engine block). It should be BIG, like #4 or #2.
As to “stacking” wire terminals, others may correct me, but I believe the ABYC and Coast Guard limit is 4 connections max on any terminal stud or screw. And that’s physically pushing it. You can get around this by using power posts (see the Blue Sea catalog pg. 102), appropriately sized for current and wire terminal size.
Ideally, the starter motor (as well as the solenoid, through the start switch) should be connected to the selector switch Common/Output along with the alternator and house loads, as roadnsky shows. This means it is
Imperative that the selector switch be able to handle well over 200A. The Blue Sea selectors are designed for over 450A.
But if your selector switch is like this Hella (
https://www.amazon.com/Hella-Incorpo.../dp/B000UKJN4O), and is only rated at 100A, it won’t do. So.......
Please send a picture of the front of the switch, and a picture of the back of the switch. The picture of the back hopefully will show the terminal markings.