SWIFT Question

[Lormalou]

Hello,
I have the task is to send 103 swift from bank A's account to bank B's account.
Questions like:
-financial monitoring of the receiving country
-FATF
-The contract.
-SWIFT Officer.
Fully regulated.
But there is a big problem, I have no access to bank A's account.
The question of whether it is possible, if you have access to the swift system in bank C, to spoof the values of MT-103 message and send the swift like not from bank C but from bank A. Or, perhaps, there are other options for performing this operation.
I apologize if the question seems stupid to someone, but I really need advice in this direction, I will be grateful for any help.