Hand Brake HELP!

I need to install a hand valve in my truck that controls both the tractor brakes and trailer brakes. I've been looking at diagrams, and can't seem to figure out where to "tap" into the air lines that already exist. And if i need some sort of check valve somewhere. ALSO, the hand valves I'm finding have only 2 ports, and to control truck and trailer brakes, would i need 4 ports. The more i talk about this, the more confused i get haha. Thanks for any/all help!

 

it's a training truck, and i need to control the brakes on truck and trailer when combined. Or, just the truck brakes when bobtailing, with out having air exhaust through the service line for the trl hook up...giving me headaches thinking about it ha