In Reporting and Analytics, click Admin, click Warehouse, click Master Items, and then click the item category for which you want to configure a Master Item.
Click Add, or select an existing master item and click Edit.
Configure the Master Item:
Configure the Name, configure a prefix to append to items belonging to the Master Item in Account Prefix, and then select the Master Group from the drop-down list.
Do not change the POS Ref #. Reporting and Analytics generates the reference ID.
Select categories for the Selected Hierarchy and the Assigned Group levels.