If LMB are your main focus, the GSH will help you to grow larger ones. You might also look into installing an automatic feeder or two, which will result in the bluegill spawning more and thus producing more forage for the bass. It'll also help to offset the competition for food with the bluegill that the GSH will bring so that your bluegill size doesn't go down too much.
It sounds as though very likely your pond has become bass-heavy. That's good if bluegill are your main focus; it's also good in the respect that you have crappie in the pond, and the large numbers of small bass will make it less likely that the crappie will overrun the pond. It's definitely not ideal in terms of producing large bass.
GSH can become very numerous in a pond or lake that isn't bass-heavy; they're not likely to do so in a pond that is. They will compete with your bluegill for food. But if LMB are the main focus, they can help.
One thing to keep an eye on: stocking GSH could take some of the bass pressure off the crappie, since GSH are more fusiform than crappie and thus more ideal prey. One of the lakes I've seen that had been overrun by tiny, very poor crappie (4-5" average and so thin you could almost see through them), had GSH in it. The lake had huge bass, but it was definitely overrun with tiny crappie. And there weren't a lot of bass in the lake; just a few monsters. That was a thirty-acre lake.
What are your goals for the lake? What's the main species of interest?
You might think about stocking a few HSB. They would help keep the crappie in check, and you could cull some bass so the remaining bass grow better, without having to worry about the crappie exploding.
