More than one additional for item &2

What causes this issue?

You are using an external Warehouse Management System (WMS). The item
&v2& of inbound delivery &V1& is assigned to more than one SLS item. As
a result, several final recipients (with the role 'UC') are linked to
this item. This is not permitted if you are using the external WMS in
conjunction with cross-docking and prepacking.

System Response

This item is not seen as relevant for cross-docking with prepacking.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.