Linking 2 Sales Orders To 1 Purchase Order No Longer Exists...Why?

Why has the ability to link 2 separate sales orders to 1 single purchase order been removed?

We have many vendors that have a free shipping dollar amount threshold. We have many customers that send in multiple purchase orders throughout the day for the same product line.  Sometimes 2, 3, or even 4 separate orders.  We used to be able to take all the customer’s purchase orders, create sales orders, and link their sales orders to a single purchase order, place the order with the vendor and get free shipping for our customers.  We no longer can do this without making a workaround.

The workaround is as follows and it is truly ludicrous to have to do:
1. Create 3 separate sales orders for the customer’s purchase orders from the day​​​​​​​

2. Put all the sales order line items onto 1 purchase order.
3. Send the purchase order over to the vendor.
4. “Break” apart the purchase order into 3 separate purchase order internally
5. Re-link those new purchase orders to the separate purchase order
6. HOPE that you can remember which PO matches which SO when the vendor’s invoices come in with the “wrong” PO since it was all on 1 original PO.

It’s just absolutely awful.

We need this functionality back.