Take it easy. Her and her sister are caring for the father’s fish who recently passed. They are learning. What’s lame is the LFS who took advantage of their lack of knowledge and promised them it would be fine to put a smaller aro with theirs.
How easy do you want me to take it? Not like I said anything out of line... don't see how you could have a giant predatory fish and think that putting a very small fish with it is going to work out fine. Also bought the new aro without doing any sort of research on Aro's beforehand, could have easily been avoided. Real victim here is the small Aro.
OP, no disrespect meant to you personally, but this should be a learning experience, if nobody tells you what you did wrong, and only coddles you, perhaps you won't learn at all. If somebody tells you something that seems too good to be true (as this should have)... do a little research on your own.