Task Design for Multiple Task Instances Confirmation at one-go

Hi,

Need clarification for the below business scenario.

As per the business requirement, we have to develop a workflow system for outstanding invoice confirmation using BPM. The proposed system design is given below:

Process design will have the following 4 steps.
First step: “Start Message Event”
Second step: User Task for Accounts
Third step: User Task for Customer
Fourth step: Terminate

Outstanding invoices will be uploaded in the system. On uploading, data will get inserted into the oracle table called “Invoice”. Adapter Notification will be created for notifying the insertion in that oracle table. If data gets inserted into the table, then it will publish the business data in the broker.

Each invoice considered as a transaction and process instance will be created for each invoice. Process instance will be created after subscribing the business document and queue the task for “Accounts”.
Tasks assigned to the Accounts will be listed in the Accounts Inbox. Accounts person will click the link in the Task Id. He will be redirected to the Task details page. He accepts the task and fills the necessary information and completes the task. On completion of the task, business data will be updated in the oracle table and task is queued for Customer.

Customer will give the payment confirmation for more than one invoice at a time. He will release the amount as a single payment for more than one invoice. The page has to be designed in such a way that customer fills the Bank Name, Payment Reference Number and Total Amount then selects the invoices for the payment and confirm and task is queued for Accounts.

Tasks assigned to the Accounts will be listed in the Accounts Inbox. Accounts person will click the link in the Task Id. He will be redirected to the Task details page. He accepts the task. He verifies the payment details and selects the status as Close then confirm. On confirmation, Account task will be completed and business data will be updated in the oracle table and process instance also will be completed.

Clarifications:-

Customer wants to confirm more than one outstanding invoice at a time. Task instance will be created for each invoice. Tasks assigned to the customer will be listed in the page. Customer fills the Bank Name, Payment reference number and Total Amount. Then, he selects more than one task and fills the payment against the invoice and confirms all the selected task instances at one go. On confirmation, all the selected task instances need to be completed and the corresponding business data need to be updated in the oracle table.

Considering this business scenario, how to make use of Customer Task Inbox, Result & Task detail page for multiple task instances completion at a time or can we take it up for customization?
Kindly suggest the best approach for multiple task confirmation