So my smartgun and smartlink have me as owner, they're connecting together so I get the bonus from the gun, because I'm using both the gun and the smartlink. Doesn't matter that they're in the Decker's PAN and being protected by the Decker. On the downside, I'm already costing the Decker 3 of their slots: My commlink, my smartgun, my smartlink. If I wanted to add earbuds, that'd be another. If my armor is smart, that's another. That's a good reason to get a form of full-body-armor with a helmet: The armor is 1 device, so my communication channels, my chemical seal, my smartlink, all are part of 1 device, the Armor. So that brings me down to 3 devices, 2 if I make the commlink part of my gun.
If the team has too many devices, then you indeed need to make the painful choice which devices are protected by the Decker directly, and which are simply on a PAN that we granted the Decker 3 Marks on.