I create for each customer a groupname
And to get the groupname in your reports I use this query.
SELECT dbo.tbl_computers.computer_name, dbo.tbl_log_threat_event.ThreatName, dbo.tbl_log_threat_event.UserName, dbo.tbl_log_threat_event.Occurred, dbo.tbl_static_groups.group_name FROM dbo.tbl_computers INNER JOIN dbo.tbl_log_threat_event ON dbo.tbl_computers.computer_id = dbo.tbl_log_threat_event.SourceUuid_id INNER JOIN dbo.tbl_static_groups ON dbo.tbl_computers.parent_id = dbo.tbl_static_groups.group_id