I'll take mild exception to the idea that there is something wrong with me, that's pushing civility a smidge what is ideally happening is that we are throwing ideas about till they stick in some manner.
Anything between two pistons is just a compressed strut by which force is transmitted from one to the other. 1N fed in one end is transfered into the other piston as 1N, however 1N from one side does not exist untill it has a 1N reaction.
You don't see the relevance of that despite the fact it is the same concept just the force roles were reversed for potential clarity nothing more.
I'm finding difficult to deal with the spurious analogies and what appears to me as refusal to properly address the issues and response.
But in response to a reasonable point: It is true that "Anything between two pistons is just a compressed strut by which force is transmitted from one to the other. 1N fed in one end is transferred into the other piston as 1N, however 1N from one side does not exist until it has a 1N reaction." No force exist without its reaction, that's Newtons 3rd law.
But that is only a complete description of a situation where there is only one force applied at one end of that strut. However, it is entirely possible to apply separate forces at both ends and have them combine. In which case, if there is an external force applied at end A and an external force also separately applied at end B, then the compression is the sum of the two forces. The resulting force at end B is the sum of the force applied there and the reaction to the force at end A. Just as the resulting force at end A is the sum of the force applied there and the reaction to the force applied at end B. At every point in the strut, and including at the two ends, there is then the sum of the force applied at A and force applied at B.