robocop321

I need to be able to record when a truck moves on to a big scale to do a weigh in. The recording needs to show the feed of the truck with a smaller feed on top of that showing the weight of the truck. i was thinking about just putting a small cheap camera in front of the scale display, but how do i get that in to the feed of the other camera recording the truck on the scale? Regards, the CCTV newbie.