Linkage between SO <-> PO

Hey All, I want to know if there is any way we can create a linkage between SO and PO for the below scenario.

Let say a SO is created and there is no Onhand in the Inventory.

So Purchasing department creates a PO in order to fulfill the SO.

Here SO and PO is total different document, so we give the scheduled ship date in SO based on the promised date in PO, and if there is any delay from supplier , we change the promised date in PO.

From here when we change the date in PO , is there any link that we can create to automatically update the scheduled ship date in SO according to PO?