Can Driver A be at fault for the accident with Driver B?

**ONLY** the involved insurance companies can and will determine "fault" for an accident.  You are wasting your time asking anyone else.

so A is holding up the cars for a friend !!! thinks car B is at fault .. Simple rule you dont hit cars on your left .

C hit B PERIOD  Unless B is backing up...which I doubt was happening.  

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Which Car are you?  Car C?   Then you are hooped. You are not GOD of the road.  You take care of your problem and you rammed "B".  "B" has hit no cars by your drawing.

That is HOW INSURANCE & THE POLICE SEE IT.

NO.   Driver A is not moving.    It is still the responsibility of the other driver's to move when their lane is clear.    And, other drivers do not have to go around driver A.   But if they do they have to yield to oncoming traffic.

Your answer is No.  Because driver A is not moving.

Morally yes they were the root cause of the accident. Legally and financially B carries the can.

Definitely yes, but only if one specific thing happens.  Driver A would have to voluntarily accept responsibility for the whole thing, and they'd have to do it on the record.  If Driver A doesn't freely accept responsibility, there is no way they would ever be at fault.

That's the rule in every state, province, territory and everywhere else in the civilized world.  If you want to take legal responsibility for something, you can have it.  That's why it says "do not admit fault" on the back of everyone's insurance card.

In that accident, Driver B is 100% responsible for the damage and Driver A was not involved in any way.  In any lane-change accident, the vehicle that was changing lanes is responsible.  Even if there's a zipper-merge law in effect, it's still the fault of whoever was changing lanes every time.  

Short answer - NO. Driver B is at fault. 

That is a pretty strange place to wait for a friend.  

But it does not matter if A is waiting for a friend, allowing a pedestrian to cross, ran out of gas, or any other reason.  Because they are not moving, they are not at fault. 

DRIVER A HAS NO CONTROL OVER B STEERING CAR INTO CAR C:

Absolutely since they caused the condition.

Obstructing traffic, wreckless operation, doing this is a PASSING only lane is especially dangerous.

But Drive B is also at fault because they failed to merge properly.

Drive C and Driver B could sue driver A and win