I found out the issue why the update was getting triggered multiple times. In the image in my first post, the first 2 parent nodes were expanded on data bind and later while editing I collapsed the first 2 parent node and edited the child of the 3rd parent node.So the expanded property of the first 2 parent nodes in the data source got changed from true to false. Since there was a change in the data source of those entries, update event was getting triggered for them also.
But now i do not want the update event to get triggered when we collapse any of the parent node because if there are many tasks and there is an option to collapse and view the chart, the user will collapse and edit a particular task. Then the collapsed node should not be considered for an update event.
So can u help me with how to achieve this, with the existing functionality in Telerik or if there is any workaround for the requirement needed.