Use map command to join multiple sub-groups from the existing linked Groups. This is useful to assign a Session ID for related events, or to correlate events across different servers or log sources.

For example, the below query joins Out of Memory events with other events that are within 30 minutes, and colors these groups to highlight a context for the Out of Memory outage:

* | link Server, Label
  | createView [ *   | where Label = 'Out of Memory' 
                     | rename Entity as 'OOM Server', 'Start Time' as 'OOM Begin Time' ] as 'Out of Memory Events'
  | sort Entity, 'Start Time'
  | map [ * | where Label != 'Out of Memory' and Server = 'OOM Server' and 
                    'Start Time' >= dateAdd('OOM Begin Time', minute,-30) and 'Start Time' <= 'OOM Begin Time'
            | eval Context = Yes 
        ] using 'Out of Memory Events'
  | highlightgroups color = yellow [ * | where Context = Yes ] as '30 Minutes before Out of Memory'
  | highlightgroups priority = high [ * | where Label = 'Out of Memory' ] as 'Server Out of Memory'

See map.