Random-Hero

So I was looking to create a new game type for me to play with a few friends, and had an idea that required the grifball game type. I set everything up, bases spawns and grif goals, but I want more than one grif ball to spawn. When I set up two capture plates and tag them as, "grif_spawn" only one ball shows up. So I tried what I had to do when setting up a CTF game and only one flag was appearing, and sign in another player, but still just the one ball. Any help?