The old soda bottle trick? Cut off the bottom and place over the top of the coral you want to target feed. Feed through the neck (cut off the narrow neck beforehand maybe) and leave it over until the coral has taken the food in.
Feed smaller food, it might look like mysis is good for them, but I wouldn't be surprised if they're really getting over stuffed from it, I believe they can (and prefer) smaller planktonic food.