Restricting Items by "Own Group"

When restricting items during the cost allocation, it would be good to be able to restrict items by "Own Group". For example, if all items are assigned to predefined (or self defined) own groups: "Milling Tools" & "Turning Tools", under the 'machines' option in the CA hierarchy, all turning tools could be restricted to Lathes when selected, or 3/5-Axis Mills when they are selected, as "Lathes" and "Mills" can be created as options in the CA Hierarchy