You can configure the chart according to your processes and needs in the “Issues” tab in the settings of all related charts:

Filter particular Epics from selected boards

All Epics from selected boards are available to select:

If you don’t see the Epic in the list, start typing the name to find the needed Epic.

You can also use common Epics for one or more boards.

Note: Filter only searches the child issues of the Epic and doesn’t search for the child of child issues.