Overstocking is a trick that works with east African Cichlids from Lake Malawi. When you say "Cichlids", that's what a lot of inexperienced fishkeepers think of. They don't realize yet how diverse the Cichlids group is, and that leads to mistakes.
South American Cichlids like those two hate overcrowding. A green terror earned its name by methodically killing fish that annoy it. They are beauties, but not social ones. If you crowd them, you may get a few months of spread around aggression, but the fish will be stressed, and in time, murders will become regular until the tank is stocked the way she wants it. Most likely, that would be with no other fish.
Please be sure you label the offspring as hybrids if you share them. They are potentially destructive to any species based breeding projects, and could contribute to the loss of species within the hobby. In my tanks, if accidental pairings like that happen, I don't save the fry.
I like the looks of green terrors, but I have never kept any because they need their own tank with no company. The industry loves them because they breed like bad politicians and are beauties. They are dirt cheap to stores and they can mark them up through the roof. But they are hard fish to keep, resources-wise.