I am very sorry to hear that
In a 10 gal, it does not take much to severely alter the tank. For example, a sudden change of salinity could cause a few snails to die which would create a large cycle... the cycle would stress out the rest of the inhabitants and cause a deadly chain reaction. A cycling tank not only creates high ammonia and nitrItes but it can also become critically low in oxygen due to the high organics rotting and a surge of bacteria; both of which require tons of oxygen. The fact that you had a heavy bioload to begin with would indicate that the oxygen was probably low at the start.
If you choose to keep the crushed coral as a substrate, it is imperative that you vacuum out the diterus during weekly water changes. It is also as important to keep the nitrAtes at 10ppm or less (fish can tolerate higher levels, inverts can not).
Back to your question.... I would keep them in the 10 gal and I also suggest you perform frequent (daily) large (20-30%) water changes using well aerated salt water that is matched exactly as the main tanks (temp, salinity); continue until the nitrAtes are down.
Keep us posted to your progress!