How to correct previous contracts and income tax statements?

To make the question general interest:
– How to correct previous contracts etc.. into new agreements in line with Law-of-mankind?
– How to describe that new contract/agreement?
– Does it legally matter that money is received on Business account, instead of Private-bank-account? (how to correct)

Background info:
i, ("A") had a contract with a company "B". 3rd party "C" paid me for dis-continuing my contract with "B" as it was in their benefit.
We (A-C)made a contract (by notary, to ensure i would never do business with "B" ever again)
money was received in my business account.

Consideration: The contract (between me "A" and "B") was not part of my company assets. So i did not sell a product.

From what i have learned in This course so far…, the contract could also be an agreement in the private" between me "A" and "C" ,
where funds should have been received into my private bank account…. Can this be corrected? if so, How to correct this?

There was NO invoice for the money received, as the Contract (in bookkeeping) explains tax authorities why a transfer was made.
So it may be possible to replace to contract?