I know this is very upsetting to you because hese are your babies.
You do not need a behaviorist for cats. They are really quite easy to understand.
They do not rationalize, nor are they capable of in depth thought or reasoning.
Everything they do is basic, logical (to them) and makes perfect sense.
In a cat heirarchy a strong kitty will always try to take over and assume the head cat position. In addition, that is always subject to changes if cat one senses weakness in cat two. Cats DO work things out in their own way and they could care less what humans (or behaviorists) think. They only respond to the energy of another animal be it feline, canine or human. Punishment is useless and counerproductive because they simply do not understand being hurt - they would just try to avoid the hurter in the future but it would not teach them anything.(except fear)
Cats do not follow a pack leader the way dogs do but they do sense their human moms energy and respond accordingly - so if you are nervous, they will be nervous. If you are stressed, they are stressed as well.
Since they have been together a while there is no getting to know you phase. They already know what to expect from each other.
However, females can be little witches. That is where they got the term catty and why it is almost never used to apply to a male.
Cats do not recognize others by sight, they depend more on scent, so if some tumil is going on in or oudoors, they can sometimes take it out on each other and begin hissing and spitting.
I know this sounds simple - because it is - just be a calm, assertive, loving energy in their lives. When they are at home , they will look to you to judge whether the environment is safe. If you sit there with a calm attitude - it will calm them. If they sense that you are upset, they will think there is something to fear so just be as nonchalant as possible and CALM.
You are on the exact right track to step in and block Callie but it must be consistant.
I would not confine either cat because they will want to get past any closed doors - cats are like that and they will be overwhelmed with curiosity as to what lurks on the other side.Plus they would be stressed by confinement (which cats HATE). . However,Alph must always have a safe spot to retreat to if Callie scares her.If she prefers to stay in a room - that's fine - she may have made it HER territory.
If Calico starts at Alph - just say SHUSH and her very lightly on the head. That lets her know (in a cat way) that the behavior is unacceptable and she will understand that feline method of correction and not be hurt, upset or insulted.
The problem is that Alpha is not defending herself against Callie who is probably head cat. This is causing her to disrespect and bully her. THe way you can help is to become Alpha defense. A cat wil only learn from someone stronger that her who is calm, assertive and puts him in his place. As soon as he shows any sign of going after her , grab her by her scruff and say NO! sharply, then gently but firmly tap his nose. You must do this every single time you see it.
Do not yell, spray water or act upset, Just immediately calmly and firmly correct her . This will teach her that her aggression will not be tolerated the way another cat would treat her - except the NO! would be a hiss and the tap would be with a paw. When Alpha sees Callie being stopped she wil gain cofidence and begin to defend herself. That will learn Callies respect and she will leave her alone.
Get a feliway plug in and rescue remedy at a pet supply to safely keep them calm.
Safe meds from a vet are:
Valium, prozac, evavil, etc
Please let me know how things are going. If you ave questions along the way I will always be here for you.
Warmest best wishes,