Create your own switcher that is switching full screen in any way you want. For how many sources as you want. You just need only 4 Layers. (Even to cut and dissolve between 16 Sources (or more)!!
This is the switcher looks like:
Try it yourself:
https://drive.google.com/file/d/1nZT4XYLdfJMqyB5Tv1qSVs_zHLoUh6lj/view?usp=sharing
IF YOU WANT TO USE IT WITH YOUR INDIVIDUAL SOURCES YOU HAVE TO CHANGE THE ENDPOINTS TO YOUR NEEDS!
To build it from Scratch, you need “N” video Sources (add 'em all to the Sources, 2 PIP-Layers, set to Full Screen - who knows, maybe you want to move the images later around, or use other effects too, maybe for your project a PIP-Window-Layer matches better? - and 2 Automation-Layers.
1. Globals
Here you’re creating the variables for TOP, BOTTOM and the changes inside the layers. You can get the API-Endpoints from the two layers. If you want to have the change-to-API-URL, simply change the Video-Image inside the layer to your source, and right-click onto “PIP-Source”-on screen-text to get this context-menu.
Collect there all later used Endpoints.
$TOP, $BOTTOM…
$TOPtoA, $TOPtoB, … $BOTTOMtoA, $BOTTOMtoB…
2. The Variants for the signals “cut and dissolve”:
To Dissolve, use a code like this:
httpRequest($BOTTOMtoA)
layerON($BOTTOM)
layerOFF($TOP)
sleep(2)
httpRequest($TOPtoA)
layerOn($TOP)
sleep(1)
layerOFF($BOTTOM)
To Cut use a code like this:
httpRequest($TOPtoA)
layerOn($TOP)
layerOff($BOTTOM)
If you have practice, you can create something like this in about 15 minutes. Add all variants to Web Control Surfaces. 
Tipp: Seperate Audio from live video content. Then you do not need to implement seperate layers for pre recorded clips. Simply add them, where they should appear.
How could you enhance it? Use/create more/other transitions, write better code, if you explore glitches. You could use this demo to play around before creating your own individual switcher which matches 100% your needs.
What else could you do?
Use keyboard shortcuts
for e.g.
SHIFT+A for dissolve to A and
A for a cut to A.
It could look like this:
