The point of initially feeding ghosties, is that they are alive and moving, dwarf lions are challenging to get to take dead foods. It is also a challenge when they are eating live food in tanks with other aggressive feeding fish. Optimally they would have initially went into an observation tank to establish a feeding routine. Not a guarantee but after initially feeding live foods, you would attempt to get them to eat dead foods. Whether they will or won't dead foods, after you have established a feeding routine, you would put them in the display tank. At this point they woiuld at least recognize the feeding routine and the foods you feeding. It is very difficult to establish a dwarf lion going directly into the display tank.
You will drop the ghosties in the tank to catch the lions attention, only drop one or two to get them to chase and eat them. You can use use a feeding stick, tongs, or even a net to block the other fish. I have a bamboo stick I use to manage my predators and make sure everyone eats. You could also try the net method, where you place a ghostie in a net and gently place the net in front of the lion, then open up the net and allow the ghostie to start coming out. Once they realize what's happening, the lion will literally swim right up to the net waiting on you to open it. You may still have to stave off the other fish. The net method works well because you can start to put various chunks of seafood in the net, and flick it up for movement, and they start to eat dead food that way. If you are dropping ghosties in, they will also learn that and come up to the top of the tank to take food, then you start switching out other food. Some ghosties will die, feeding fresh dead ghosties is a good first introduction to dead foods, ti get them to start eating dead. Them eating from tongs or feeding stick takes time, try using dead ghosties afer you have them established.
I write alot of threads on the care of lions, I suggest you click my name and "find all threads".