I firmly believe I have explained it the best way I could and helped you better understand the CPFP method.
You didn't. odolvlobo is right.
All you need to do for doing CPFP is spend the fund received in the unconfirmed transaction with a high fee.
Also note that, for doing CPFP, you should spend the coin received in the unconfirmed transaction, not any coin from the receiving address.
So, it's not accurate to say make a transaction from A2 to do CPFP.