A few notes please.
I have written before that I find it rather unfortunate that people keep delicate species with specialized diets that eat other delicate species with poor survival records.
PLEASE, never buy Linckia,Fromia or any reef safe stars to feed to these. Very few survive, and are under intense pressure from this hobby as well as the craft and souvenir trade. I include chocolate chips in this as well. Walk into anh craft store or shell shop at the beach, and take a look at all of those dried stars, most of which are Linckia, choc chips (often with ugly dyed colors) and sand sifters.
What the heck is a "feeder starfish?" The cheapest solution (and most ecologically responsible) is to get yourself a refugium or sump, collect the small white Asterina stars that reproduce like weeds (and people are always picking them out of their tanks and tossing them)...there is a thread on these stars every week). Maybe offer to take them from people. Toss them in the refugium or sump, and let them reproduce.
Look into seeing if your shrimp will take frozen seastars, where you can cut a hunk off and feed it (but it makes the most of a star).
I do not believe they eat brittlestars, and if you don't want it, trade it in to an LFS. What kind of brittle is it?