Regarding the functionality you aim to achieve, I can suggest you two approaches:
1. Use the IsSeparator
property for the items that needs to be represented as parent. You can even modify these items using css style rule, in order to enlarge their font size and so on. Please refer to the following documentation article, providing more information on the usage of the property:
2. Use a RadDropDownTree, which you can supply with hierarchical data source, in order to visualize the needed rendering and represent the parent->child relation between the items. See DropDownTree demos:
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