I am glad you made this post. In order for us to help you, you really have to give us a whole bunch of info. Trust me. If you put in the time and effort to give us every last detail you can think of, we as a community will help you fix this. Here are some starter questions. Please answer all these AND whatever other info you can think of.
1 How long have you had these snakes?
2 are they kept together in the same tank?
3 Where did you get your snakes from?
4 How old / big are your snakes?
5 What is your setup / temps / hides / substrate / way of measuring temp and humidity / humidity % / type, size of enclosure
6 What exact steps did you take before resorting to assist feeding?
7 how often are you feeding?
8 What exactly are you feeding, and what is your procedure when feeding (before trying to assist feed)
9 How much are you handling the snakes?
10 When is the last time they shed? How did that shed go?
I know it will take some time to answer all these quesitons, but answer in as much detail as possible, and be willing to hear the replies. I promise you we can turn your snakes around.
Mike