We have to make cooperative project with another department. We'd like to make it strictly accessible only to users in Project (from both departments)
So I created second Space, added specific access rules for the project users.
Our first Space S1 is the Default spaces ( and there are all our internal department projects )
We don't have enough knowledge to make such S1 spaces as Public and all our department projects are in.
The questions are:

1. Is that security problem ?
2. Can be changed Default space to S2, S3 or else ?