Customer Sub-ledger account determination at the time of billing

In a company code/Sales org. (XYZ) there are two customer master records A1 and A2, in the partner functions of the customer master, they have maintained with sold-to-partiesA1andA2respectively, ship to parties are A1andA2 respectively,however the two sold-to-parties will have same bill-to partyA2.

In the above scenario, if I create an invoice for sold-to-party for A1, which sub-ledger account will used?

Option 1:

Dr. A1

     Cr. Revenue

or

Option 2:

Dr. A2

     Cr. Revenue

If possible please share any standard SAP document where the logic is documented.

Thanks,