I've attached a crappy foto of my 4-port Stridsberg Multicoupler... but you should get the idea. There are cheaper, less effective ways to do it, but this gives me the very best results for my application, and it's very easy to set up.
I have over 40 Uniden scanners of various models.
Also, up to a dozen USB dongles running SDR#.
And several Icom IC-R7000 radios.
And a few others.
I have 8 antennas. (varies at times).
All but one have a pre-amp.
I feed 32 scanners including my Broadcastify feeds with two of these and an ST2 antenna:
NOT with the pre-amp shown in the photo.
An RF Bay, Inc. LNA-1000 pre-amp is connected right at the base of the antenna
I have one by the computer, one bedside, and one in my PU truck. The one in the truck is plugged into an 800 something converter that outputs house current. I believe the power from the wall-wart is 18 volts. Conventional Wisdom (lol) always says "Increasing the signal just increases the noise". CW, you're probably right, but still, I wouldn't leave home without it. Big decrease in missing syllables/words during long transmissions by my experience.
I've got three scanners in my garage I listen when working there. One is a portable and monitors a local system, thus not needing any increased reach from an external antenna.
The other two are mobile scanners, but on a single 12 V power supply. I looked into getting the multicouple mentioned above. When crunching the numbers, I found it to be less costly for each scanner to have its own antenna in the attic.
At the fire station, where we had access to a taller tower to which a scanner antenna could be mounted, we did use a multicoupler. Several scanners are "supplied" that way. Given the length of the antenna cable run involved, we used LMR 400 cable from the antenna to the multicoupler.