Assigning Material Components to Standard Networks 
You can also assign material to a standard network when you create the standard network.
Activities. If no material components have been assigned to the standard network yet, the Bill of Material dialog box appears.
If material components have already been assigned to activities of the standard network, a dialog box appears in which the corresponding BOMs are displayed.
The further procedure is the same as if no components had been assigned.
If several BOM alternatives exist for the material, a dialog box with the alternatives appears. Select an alternative. A list of the material assignments appears.
The system assigns the BOM items to the activity.
The activity overview appears again.