@SvenYargs Yes, I think you are right. Do you want to add this as an answer?

RE: "as little as possible" economize

@J.R., you are right, I've deluded myself. Then not amicable, but person B remains in the partnership amicably to mitigate the discomfort? I apologize for being vague. I feel self conscious about the specifics, and tried to, obviously unsuccessfully, abstract the scenario to a somewhat generic picture

@KristinaLopez, yes, person B knows the nature of the information person A withholding, but not the details. As I keep looking for a word or phrase that may represent this, I came across this: en.wikipedia.org/wiki/Master_suppression_techniques the background of the "strategy of social manipulation" fits the bill, and the specific technique "withholding of information" is specific (although the examples would not include the scenario I posted). Still, I am looking for word or phrase that encompases all of it

@BenLee, The information is not vital at this stage. If partnership continues, person A will have to disclose this information. Person A looses nothing by disclosing this information. But I suspect is a way to establish a relational dynamic early on the partnership. Regarding what stage of the partnership, is in the early stages.

@KristinaLopez The information is legal and pertinent to the partnership. The information could not be used to blackmail nor for coercion. But the withholding of non-vital information in the partnership forecasts withholding of vital information in the future. Person B has an incentive to maintain partnership given likely gains.