Change PO net price based on user-defined date

Dear experts,

Urgent!!

Purchase order item net price determined based on purchasing info record. We can change Pr. Date Cat to retrieve the corresponding PIR price into PO item net price.

Now the requirement is: client wants to add one custom date into PO header, then determine the item net price based on this custom date. Also when the client click button item->condition tab->button 'Update', the price should be still determined by our custom date.

Experts, is there any ideas? Very appreciate if any inputs.

Regards,

May.