Are you coming with more than 20 people? Then it's best to make a group request via The Streamers' contact form.
The organisation will consider all group requests and will approve them in order of request and based on availability. If you submit more than one group request, only one request will be approved in order to give as many people as possible the chance to get tickets. You cannot express a preference as to which request will be honoured; this will be done in order of request and availability.
In a group request, you can request both sitting and standing places in the same request.
If the request is approved, you will receive a confirmation e-mail. Within 10 days you can still change the request. So this means you can increase it (provided there are still tickets available) and decrease it but not less than 20 tickets.