Questions about example sentences with, and the definition and usage of "Agreed"

A: that may or may not be the case, but it’s not what “agreed upon” means here ... here, it simply means “decided beforehand” between the child and the adult, even if it was originally the adult’s idea

“preordained” implies that it was decided by a third party—possibly by fate, or God—beforehand ... it’s too grandiose a term to use here...

you also cannot “agree [something] upon [someone]” in English ... it’s a good question, but we just don’t have a structure like that in English ... two (or more) people mutually “agree upon” something ... which means they “come to an agreement” on / about a topic

A: an agreed upon fact is something that most people believe to be true. so this sentence is stating that this upcoming statement is believed to be true

A: 'by the agreed upon date' means anyday anytime before that day. on the other hand 'on the agreed upon date' means on that exact day that two parties fixed upon discussing.

like 'let me know your opinion by the agreed upon date' means you can express your opinion anytime before and on that day, and 'let me know your opinion on the agreed upon date' means you will express your opinion on that specific day.

A:

A: We all agree on this point.

A: Check the question to view the answer

A: @tjstkdn
The gerund could work if you say "to putting" not "on", but I personally prefer the infinitive. I am not sure why it just sounds smoother.