ZBook Thunderbolt dock plus additional USB-C monitor adapter

[webbd]

I work as a software solution architect and cloud administrator and typically need to spread my work across multiple monitors. 

My desk at work uses:

• HP ZBook G9 with 128GB RAM and 16GB NVidia graphics
  • Laptop primary screen 
  • HP G4 280W Thunderbolt dock
    • 2 - 34" 4K Samsung monitors
    • 1 - 1K ViewSonic monitor
  • 1 - 1K ViewSonic monitor connected to the Mini-DP port

I worked from home during COVID and have a more complex setup for when I am not in the office.

• HP ZBook G9 with 128GB RAM and 16GB NVidia graphics 
  • Laptop primary screen 
  • HP G3 Thunderbolt dock powered independently from the laptop and connected using a Thunderbolt cable (not the custom power/Thunderbolt cable that came with the dock.
  • 7 - 1K monitors connected to the dock and the mini-DP port
• HP ZBook G4 with 64GB RAM and 12GB NVidia graphics
  • Laptop primary screen
  • Selore & S-Global Thunderbolt hub
    • 2 - 1K monitors
    • 1 - 0.8K monitor
  • 1 0.5K monitor
  • Microsoft Power Toys Mouse Without Borders (allows control of both computers from a single computer)

In all of this, I have acquired quite a few monitor adapters, including USB/VGA, USB-C/VGA, DisplayPort, USB/HDMI, USB/DVI, etc. to connect monitors to the various ports on the ZBooks and Thunderbolt docks

When not using my ZBook G9 at home, I frequently connect my ZBook G4 to the G3 docking station where I can run 10 screens total (8 - 1K plus 1 0.8K along with the laptop screen) by additionally using the laptop's USB, VGA and HDMI ports

Both laptops have dual Thunderbolt ports.  I can connect the Thunderbolt docks to either port per laptop.

My problem: Neither laptop recognizes both devices when I connect:

• Two Thunderbolt hubs
• One Thunderbolt hub and one USB-C/VGA adapter
• Two USB-C/VGA adapters

My question: Does anyone know how to get either ZBook to recognize additional USB-C connected monitors when one of the Thunderbolt ports is in-use?

(Another HP G3 hub would probably address my needs, but it's a roll of the dice on whether I can get one in perfect working condition.  Instead, I'd really like to make full use of what I currently have, including additional USB-C-VGA adapters.)

Thanks in advance.