How to populate PO numbers from Order Management to service contract

Customer has a scenario, where a single subscription item has been booked with multiple PO's in the sales order. When the order is progressed and closed, system creates a contract. In the order header the PO number is "SEE_LINES". But in order lines they have entered different PO numbers. When the service contract gets created, the header PO number "SEE_LINES" is defaulting in the service contract. But they want to populate the individual PO numbers to be carried from sales order to service contracts. Because when invoice gets generated for the subscription items from contract, in the invoices it gets