Just an observation: you’re going to get better results if you T a 6" into two 4", which are then reduced, instead of reducing it and then Ting it. This is because the area of 2x 4" ducts = 1 6" duct. You also want to reduce as close to the tool as possible, and avoiding reducing whenever possible.
Also anything that’s smaller than about 2.5" usually isn’t worth hooking up to a Dust Collector, you’re better off with a dedicated shop vac, since the small opening makes the high pressure, low volume output of a shop vac a better fit for the application. Depending on how the router table is setup you might be better off with a 4" duct on a custom fence than the 2.5" it comes with.
The connection for the Delta Bandsaw is almost worthless for a Dust Collector because by the time you’ve reduced it from 6" down to 1.35" you’re not going to get anything through it. (I checked this with my hand when the Bandsaw was first hooked up to the DC) So your options are the dedicated shop vac, or a custom made 2.5 or 4" port right under the table. Once again two 4" ducts = 1 6" duct, and you’ve already got one in the body, so perfect solution is 4" duct right under the table. OTOH, this is more work, so the shop vac is a quick fix.
I would not mess around with connecting the drill press to anything. Drill presses don’t create the fine dust that causes health problems, so really what you want is a chip collector. Best chip collector is a dust right 4" nozzle on a flexible hose to clean up after the holes are drilled. Anything else is going to get in the way and not used.
You also might find that the Miter Saw dust collection works best with a combination of a dust collector to get the big dust from the shroud, combined with another dedicated shop vac hooked up to the built in dust shroud. This is more a nice to have than a must, but it will increase the dust collected.
I would not hook up anything to the Rigid belt/spindle sander, the dust collection on in stinks unless you build a dedicated shroud. The Grizzly is almost as bad, with it’s tiny 2.5" ports.
If you do decide to go with a shop vac hooked up to any of the tools the cheapest way to get separation is one of these Dust Toppers:
https://www.homedepot.com/p/Dustopper-High-Efficiency-Cyclonic-Dust-Separator-12-in-Dia-with-2-5-in-hose-36-in-long-with-2-Sweep-Elbows-HD12A/315749552
DeWalt is also about to release something similar to the Dust Deputy. I wouldn’t buy a dust deputy since the cost is about twice the HD Dust Topper:
https://www.amazon.com/dp/B096N3NW4Z/?tag=toolguyd-20
Also make sure that any shop vacs used in such a manner have a HEPA filter and bag, otherwise you’re just creating a dust pump, as all the fine dust will just go right through it.
