Where to add code after every "Un-Friend" Action

Hi All, I have some code cleanup I would like to perform after every "un-friend" action on my site ( I have Modzzz's circle mod and I would like to remove the user from circles if they unfriend) but I'm not sure where to put the code.  I've narrowed it down to : 

1. _deleteRequest in BxDolCommunicator.php

Question: Is there anywhere else I need to put code for the "Un-Friend" action? Also, any issues with adding code here? Please let me know your thoughts/ideas about this. Thanks.

Ideally, you need to modify the "My Circle" modules and use the Alerts system to do this instead of making adjustments to Dolphin core code.

@Modzzz 

Have you seen my inquiry? I send here with the boonex system and an email.

Putting solution here to help anybody that runs into same issue: 

Problem: I have some code I would like to run after every "un-friend" action on my site ( This is in relation to @Modzzz Circle mod, I would like to remove the user from circle if they un-friend each other) . As mentioned above, it is not recommended to alter core code but make the changes in the module itself. So I need to use Dolphins event subscription service which uses "alerts" to pass event notifications which I can handle in my module.

Solution: 

1. Create the alert handler method. 

Inserted the following into the sys_alerts_handlers table in database:

INSERT INTO `sys_alerts_handlers` VALUES (NULL, 'modzzz_circle_friend_delete', '', '', 'BxDolService::call(''circle'', ''response_friend_delete'', array($this));');

Create the corresponding method in BxCircleModule.php: 

function serviceResponseFriendDelete ($oAlert)

    {

        ....

    }

2. Create an alert that will receive event notification and call up alert handler method

Inserted the following into the sys_alerts table in database:

INSERT INTO `sys_alerts` VALUES (NULL , 'friend', 'delete', {Must be id of the corresponding row in sys_alerts_handlers table});

Note: I got the name for the un-friend action event from BxDolCommunicator.php : line 261.

case 'sys_friend_list':
                $oZ = new BxDolAlerts('friend', 'delete', $iID, $iProfile);
                $oZ -> alert();
                break;

If anyone has anything to add, please feel free. Especially about how the BxDolAlerts work exactly, thanks. 

The following function should work to remove both from each other's circle :

    function serviceResponseFriendDelete ($oAlert)
    { 
        if (!($iProfileId = (int)$oAlert->iObject))
            return false;

        $iAssociateId = $oAlert->iSender;
 
        $this->_oDb->removeFromCircle($iAssociateId, $iProfileId);
        $this->_oDb->removeFromCircle($iProfileId, $iAssociateId);

        return true;
    }