screen sharing - how to return control to client

I have two Macs on the network, in separate rooms. I want to remotely connect to one Mac from the second and control it. To do this, I have enabled screen sharing on the host (remote). I then use the network on the client to browse the Mac and log in. The desktop appears. I can use the mac remotely.

How do I switch control back to the host machine without disconnecting? The mouse and keyboard are captured by the host (remote).

I want to have both screens up and control both devices by moving my mouse in and out of the remote display window.