Spawning Killballs

Ok so I’m trying remake maps from reach and halo 3 so we have bcustom games among ourselves to play. Remaking destruction derby, a version in which you have to avoid kill balls but also want to knock other players off the map, is fun but at the same time there is one thing in my way. Killballs being the 2 problems, first off I don’t get how you get them to spawn back, also having several of them spawn after 3 minutes. Last problem being that when they roll off the edge of map on impact, hitting the bottom of the entire map, forge wants them to delete theirselves therefore making this even more impossible to make. ANY SOLUTIONS!?