The little sunfish you refer to are probably the bluespotted, banded and blackbanded sunfish. The bluespotted is by far the most common and widespread of the three. The blackbanded is the least common and most restricted and is endangered in a number of states. They make great aquarium fish however, not the best forage fish. They are rarely found in habitats where they compete with other more common game fish like BG or LMB. They have low fecundity and require very thick vegetation to seek cover in. Also, their habitat preference is for soft acidic waters. That precludes HSB as a predator of them as HSB like hard neutral or slightly alkaline waters. I stocked a few bluespotted sunfish in my forage pond where they have just barely hung on without predation with extensive food. Once predators go in, I suspect they will not last.
There are other small sunfish species to choose from. In the Midwest, the orangespotted sunfish which has been talked about on the forum before is an option. They are however adapted to conditions similar to FHM. They may be a reasonable additional forage for SMB, but I doubt they would do well in a LMB pond. In the south there is the bantam sunfish and also the spotted and redspotted sunfish which are a bit larger than the previously mentioned sunfish species. The dollar sunfish is also found in the south and remains quite small. Again, most of these species are adapted heavily vegetated waters where competition from BG, LMB or other more common game fish is limited. There are also the longear and redbreast sunfish which will reach 8"-10" in size but can do OK in ponds with more common game fish.
