The short answer is, Yes.
Event detail changes are inevitable, especially where the venue has flexibility around numbers and available tickets quantities vary.
Note: Only Client Administrator's can edit an event.
Update the number of tickets
On [BUILD EVENTS] window, locate your event then [Edit].
From the [DETAILS] menu tab update the [Ticket Count] to the desired number of tickets available for your event.
Now that you've increased the number of tickets available, you'll need to allocate and assign these additional tickets.