Manually 'Grant' last event places by 'Pending from waitlist' and override 'max participants'
Currently we use this as a workaround:
In CRM/Event/Form/Registration/ParticipantConfirm.php we manually edit the emptyseats to allow the registration to finish.

//Allow confirmation even when waitlist is still on
$emptySeats = 99
//$emptySeats = CRM_Event_BAO_Participant::pendingToConfirmSpaces($this-&gt;_eventId);


In this way the event is still full and new registrations will be on the waitlist. But the people I manually edited to "pending from Waitlist" can finish their registration.