There are three options for “Propagation of Procurement Group”:

• Leave Empty – this will merge requirements
• Propagate - links related transfers (Odoo creates  procurement groups as needed)
• Fixed – this allows you to specify a Procurement Group that will apply to all of the transfers created by a Rule.

The main use case for specifying a Fixed Procurement Group was on Reordering Rules to stop requirements being merged, but that seems to have stopped working!

Please follow the below use-case for your better understanding:

Example: "Fixed" vs. "Propagate" in Procurement Group Propagation

Scenario:

You have a main warehouse (WH1) and a sub-warehouse (WH2). The sub-warehouse (WH2) gets stock from the main warehouse (WH1), and WH1 purchases from an external vendor.

Case 1: Propagate (Creates Separate PO/MO per Demand)

    A Sales Order (SO) is created for 10 units in WH2.

    The procurement rule at WH2 requests stock from WH1.

    WH1 propagates the demand and creates a linked PO to the vendor for 10 units.

    The PO to the vendor is directly tied to the original SO, meaning if the SO changes, the procurement gets updated accordingly.

Case 2: Fixed (No Propagation, Predefined Replenishment Rules Apply)

    A Sales Order (SO) is created for 10 units in WH2.

    The procurement rule at WH2 requests stock from WH1, but instead of propagating the demand dynamically:

        WH1 checks its existing replenishment rules.

        If WH1 has a reorder rule (Min/Max stock), it triggers a PO only if stock is below the minimum threshold.

        The PO is not directly linked to the Sales Order.

    Even if the original SO is canceled or modified, the PO at WH1 remains unchanged since it follows a fixed procurement plan.