OBS not allowing me to select multiple sources.

I am having a problem with OBS and Windows 10. I have a hall set up with three webcams and then a camera and laptop via USB/HDMI capture dongle, So five sources in total.

In device manager I have renamed them all so they have friendly names such as rear camera, front camera, lectern, PowerPoint et cetera. However when I go to set up a source from video capture device in OBS, I am given the option of either “webcam” (x 3) or “USB 3 Capture device” (x 2) OBS is not picking up the new name. Zoom has the same issue, so it’s a bit of trial and error to pick the correct source!

But there is a bigger problem with OBS. I want to create a scene with both the lectern camera and PowerPoint, both of which are attached via the USB capture dongles. It would appear that I will display either one or the other, but not both. The same goes for the webcams. Once I have selected a webcam, it will not let me select another one as a source. I just get a black screen. It’s almost like it will only allow one webcam and one USB capture to be available at any time.

I am deducing (correctly or incorrectly) that it is getting confused as it is only seeing 2 different inputs (webcam or USB Capture card) and not 5 different inputs.

Does that sound right? Can anyone suggest how I can get around this?
Thanks in advance.