You CANNOT keep dwarf seahorses with anything else. You might get away with very small snails. NO shrimp, especially not peppermint shrimp, and no gobies, or fish of any type.
Try to get some captive bred dwarfs, and you might find someone who has them feeding on frozen foods. Otherwise, you have to hatch brine for them EVERY day. No feeding brine from the store, they have to be fresh hatched.
Dwarf seahorses(or any seahorse species) are very high maintanance and not for the light of heart. They are extremely rewarding to own and watch, as long as you're willing to set them up correctly and raise them responsibly.
You can try going to "
www.seahorse.org " for more info.