Today was bath day since I have to work tomorrow. I bathed Loki with the other three and let them play for about 90 minutes. These crabs have zero interest in each other as far as I can see. Loki did change shells twice and finally settled on the second shell. Loki is still very scared.
When I put them all in the main tank they didn’t all run into their hut and hide for a change…but I redecorated a bit so maybe they like it better 
The newbies seem okay… the one crab is still under the sand and the teeny green shell one is still in the same place but not dead.