I would stick only with non reef safe seastars such as chocolate chips, red Africans, general stars or similar. Do not buy a "reef safe" star such as a Linckia or Fromia which require mature and larger reef tanks. The other stars can be spot fed, so are more suitable for a tank with predators. However, if you ever entertain the idea of adding a puffer, trigger or larger wrasse/angel, then I would not add a seastar at all....these fish are natural predators of seastars.
BTW, why do you want to get rid of bristle worms which are very effective scavengers especially in a predatory tank? Besides, I am not sure that the shrimp would definitely try to feed on them anyway. It is unlikely the stars would be effective at it.