purchase_all_shipments

purchase.order: Replaces the 'In Shipments' button with an 'All Shipings' button to view all pickings grouped by procurement group.
purchase.order: Adds computed fields to count and list all related pickings for a purchase order.

This module enhances purchase orders by replacing the 'In Shipments' button with an 'All Shipments' button that displays all related pickings, including those chained through procurement groups.