I think it depends on the booking type.
You can book either room or bed.

We could book 3 beds in the one booking and stay with others.
Or choose to book one room for 4 people.

I have stayed in hostels before with many random people and so far, no terrible stories!

Nick

On 2017-10-30 18:13, Johannes Zarl-Zierl wrote:

Hi Thomas,

I haven't booked yet. And we are just three...
Shall we book a room for four people and hope for the best. Maybe we can
add some information while booking and request to have someone with
chance mentioning "FSFE/Free Software Foundation Europe Community
meeting" (or parts of it) to our room risking that we are just three and
have on 'stranger' in our room?

I thought full-room bookings mean that one books the room and pays the same
amount whether there's one or four people in the room?

Cheers,
  Johannes