Can I query the child of child work items and publish them on a board?

pradip10  - In short, No.
While it's possible to get such results using hierarchical query, the dashboard widgets only work with flat result sets 😞

I find the following workaround a useful coping technique:

- Write query 1 to find the children (Features) of the Epic.   Use: Parent = Epic ID. 

- Write query 2 to find the children (Items) of those Features.   Use: Parent "in" list of Feature IDs (comma separated).

- Then use Query 2 with the chart/analytics Widgets on a Dashboard to represent the query result set however you wish.