Will this dual display/KVM setup work?

I can't find a 'monitor' section anywhere in the forums. This was my next guess. If a mod feels it should be moved elsewhere, feel free.

I'm curious if this setup works.

2 displays A and B
2 machines 1 and 2.

(A and 1 being better/primary over B and 2)

I'd like machine 1 to use both A and B as a dual display, but be given the option (through a KVM switch) to turn B into machine's 2 display while leaving A as the primary (only) display of machine 1.

Note, I DON'T want to flip BOTH monitors back and forth with the kvm switch, I know there are dual display kvm switches out there. I only want the dual display on machine 1.

Here's a diagram

A B
| |
| |
| KVM
| / \
| / \
| / \
1 2

I imagine the switch FROM dual display TO using B for 2 would be easy. What about the switch back? Would a new monitor added to 1 instantly pick up as the secondary display and immediately function as such?

Even if you don't have a perfect answer, any idea where I could go to find one?

Thanks.

I have this exact setup, yes it works fine, you can find an inexpensive usb 2 port kvm on newegg for around 20 bucks.

It takes about a second between switches for the machine that you switched to to pick up the mouse and keyboard inputs and video transfer is almost instant.

I run a 3 monitor setup with 2 4850's and also use a USB KVM. When I hit the switch monitor 3 automatically switches over to whatever the KVM is plugged into (usually my laptop or a machine I'm fixing). Sometimes I will have the USB plugged into the KVM so the keyboard and mouse switch as well. You should have no problems.

I've been running a similiar setup for years and never have any problems. A good KVM when switched will still keep the other source active (ie. when I switch to my laptop my main desktop doesn't disconnect the monitor and start moving my icons or programs, it simply sees that the monitor is no longer active on the system, kinda like the monitor went into sleep or standby.)