I'm using a raspberry pi to control some relays hooked up to some lights. I am a controlling the lights via PHP web controls. I've reached a barrier in which there aren't enough GPIO pins to control all the lights I would like to. If I were to buy a second RPi, would it be possible to control it via the same page? I know basic HTML and I know I could just add a link that takes you to the second pi's IP address, but I would like to build a cohesive GUI in a single webpage.