Hello. At first you need a hardware switcher that can have as many outputs as your cameras. Then a way to have as many hw inputs as you need in vmix. I think personally that the most cost effective way to do this,is to buy hdmi or sdi (depends on your cameras)-->ndi like Kiloview E2 NDI so you can have hdmi output for any hw switcher and ndi out for vmix input

Thanks for the quick responses, however, I think my initial question may have been a bit misleading, so I apologize for that.

I've been a vMix user for over 5 years and very well versed on its video switching capabilities and on how to actually bring the cameras in. What I was attempting to solicit suggestions on is how to offload the processing load of those cameras to a hardware switcher WITHOUT loosing the ability to record those cameras using the Multicorder.

Since I started using vMix at my church, we've always brought in 3 cameras via HDMI and 2 via NDI. While this has worked well, there have been moments where system load has spiked. So we recently purchased the ATEM Mini Pro ISO and moved all cameras to it. So now I guess I'm having a bit of buyer's remorse and wanting to have the Multicorder functionality back. I understand that this may not be possible, but I don't know what I don't know.

Seems like the most viable path forward would be to record locally either at each camera or on the ATEM (something I'd like to avoid, if possible).

Kiloview has a multichannel NDI recorder.
DataVideo a 4Ch HDR-90.
Medialooks, Kiloview have a software multicorder.
Yololiv Yolobox Ultra has 4 HDMI, ISO, HDMI out and maybe worth looking into closer. I use it for smaller jobs where you get away with basic switching.
Atomos has a 4 Ch recorder as well that you can use as switcher, records iso and switches.

Hope that helps you a bit.

An external I/O Chassis is the best option to me, as I can place an 8 input capture card and have 8 cameras in your multicorder....I use an internal capture card in a desktop and capture all cameras, plus the output mix as well.....