Add something like iProperties.Value("filename.ipt", "property tab name", "property name"), where "FILENAME" is the parent of a DERIVED component, something like "iDerivedParentFileName". Values such as Mass, Volume, etc could then be used for easy comparison between a modified derived "child" and the parent.
The derived component already knows about the parent -- if you right-click the "body.ipt" entity in the browser, one of the options in the pop-up menu is "Open Base Component". Also, if any of the parent (base) component parameters are exported to the derived child, the name of the base component appears in the parameters list of the child. So why was this so conspicuously left out of the iLogic command set?