This is my comment via T-Mail, after I asked her to show me what the root-ball looked like. I had already addressed the light issue with her.
"Yep, I think we probably have discovered the problem. The plants are literally dying of thirst. Soak that root-ball in a large sink or a large bucket of water overnight and then let's up-pot them. You don't have to split the plants up but you certainly can if you want two separate trees. I make all my own media, but yes, regular potting soil is OK. Go to a pot that is about 4" wider.
This is one of the problems when purchasing nursery-grown trees. That large nursery probably had an automatic watering system and these trees were perhaps getting a slow watering daily or even twice daily. They don't grow plants like a hobbyist would. Everything that a big-box store would carry is grown in huge, commercial nurseries."
