Is the monitoring of linked websites affected by Piwik updates?

I like the Piwik visitors monitoring very much, although I don’t understand the system.
I have it installed on one website and linked a number of other websites to that installation.
Can I update a Piwik version on the main website without losing the tracking of the linked websites? Do I need to re-establish codes at the linked websites or does an update not affect those linkages?
Since I once lost the monitoring of a linked website by Piwik I hardly dare to update Piwuk anymore. Or is that only possible when that linked website itself is updated (and the link code maybe over written)?