Single Bill for new items added in Purchase order

In NetSuite, we're facing a situation where we want to include additional items from purchase orders into an existing bill. However, the current process only allows us to create a new bill for these extra items added in the Purchase order. We're looking for a solution that enables us to either merge these bills into one in NetSuite or edit the existing bill to include the remaining items from the purchase order, ensuring that the purchase order reaches a fully billed status.

Even if we add new items manually in Vendor bill, the purchase order will be in pending billing status.