A computer-implemented method and system for managing financial institution customer transaction accounts involves issuing a relationship presentment card with a relationship identifier unique to the customer that is linked to a plurality of the customer's financial institution transaction accounts via pre-defined parameters for determining to which of the customer's linked accounts to post particular transactions with the relationship presentment card. Thereafter, when data for a transaction with the card is received by a processing platform of the financial institution via a merchant acquirer and a card association processing network, the card processing platform of the financial institution identifies a particular financial institution account of the customer to which the transaction should be posted according to the pre-defined parameters based on the transaction data and posts the transaction to the identified financial institution account of the customer.