RadTimeline for WPF does not support hierarchical data. The feature that comes close to this feature, but only when there is one-level-deep hierarchy is the Grouping feature. You can check our Grouping demo
for a quick overview of the grouping feature - the demo is SL, but our SL and WPF demos share code. You can download our WPF demos from here
Check out Telerik Analytics, the service which allows developers to discover app usage patterns, analyze user data, log exceptions, solve problems and profile application performance at run time. Watch the videos
and start improving your app based on facts, not hunches.