I have a Honeywell pet safe hard wired 8 port alarm system, I'm a joiner and have a lot of tools in the van I wanted to put a cordless sensor in the van and one in a post box (if someone puts their hand in to steal post), I've been told this can be done with doubleing up a port and then attaching a nova 4 and attaching the two sensors to it, but he was not sure how it's done does anyone know how to and a list of things I need to buy or even a better method