You shoul say:
There is no dispute that the car ahead of me only felt one impact. There is no dispute that the truck hit my car from the behind.
There is a dispute about whether the one impact felt by the car in front of me, was caused by my car or the truck.
There are two possibilities to explain the fact of one impact.
(1) as the adjuster explained, I could have hit the car ahead of me first, moving it so far away from me that the car did not get hit again when the truck hit me.
(2) or a simpler explaination is that, I fully stopped WITHOUT hitting the car ahead of me, but the truck hit me from behind and caused my car to move forward and hit the car ahead of me.
The simpler explanation is supported by the photographs I took at the scene of the accident. The photos show that my car's front bumper was touching the back bumper of the car ahead of me. The photos also show that there are some distance between my car and the truck behind me.
The adjuster's explaination requires some distance between my car and the car ahead of me, which does not exist in my photos.
Therefore although the adjuster's explaination is hypothetically possible, it is not what happened in this case.
