Here is how I would design it. Each action should have the logic to retrieve/populate the initial set of data and to process the form submission when the user submits it. An "if" would be needed in each action to decide if we are handling a form submission or a form population. For instance after completing the logic of processing the submission of data in CustomerAction I would redirect to BankAction which would retrieve the bank information and populate it into the BankActionForm then forward to the
jsp to display the page. After the user fills in the form the data would be submitted to BankAction which would process the data and redirect to the next action in line. That way your action/forms are mostly self contained and the code within is only concerned with the data related to one entity (like bank or customer).
Hope that helps some.