Gary, Give Hershey time. And introduce SLOWLY! He can learn to adjust to the other cats, but he needs to adjust to you and his new surroundings first. Even foster cat Meesha (who was thought HATED other cats) learned to adjust to living here with many fosters. And also Bailey and Lizzie (especially Bailey) she hates other cats with a passion, but they co-exist with them just fine, but it took time.
Let Hershey learn to love YOU first, then worry about the other kitties. (I know it is hard, I am always impatient too