Background:
I'm writing a professional (technical) report in which I want to express the following in one simple sentence: The whole report is written based on a certain assumption, except one part that's based on a different assumption. (Let's say a battery has 10 Volts in parts of the report, and 12 Volts in another part). This means that one part of the report is "wrong". I want to express that the way I'm doing this has been "approved" by our client. The part in parentheses is just to illustrate the context.
(In most of the report 10V has been used. However, the voltage is actually 12V. 12V has been used in chapter 2 only.)
The usage of a different voltage in chapter xxx only, is done in agreement with client name.
However, the last part of that sentence doesn't seem good to me. I think it's grammatically correct, but not something a native English speaking person would write. Can I say / write: "... is done in agreement with"?