First thing would be to get them all their own homes. They are solitary animals and will stress each other out when put together. With the size difference the larger one is likely pushing the smaller around. Make sure temps are setup properly, ~80 ambient with 90 hot spot, and humidity 50-60%.
Was the nonfeeding one eating from where you bought them?
Perhaps try leaving her in her own cage when she's comfortable for feeding rather than adding the stress of moving.