An alternative is to create a bunch of sheets yourself and assign 'all players' edit access to them. When people log in they can claim one and use it and the next time you are there you can just remove the 'all players' in favour of the specific players... less elegant that the other solutions but saves having to have a player being able to see behind the curtain (co-gm) or needing to have pro access (API - which i highly recommend but that is neither here nor there).