Do we more or less know how many days worth of supplies they have to keep both up there if needed?
PS. There was a nice movie released 1979 about that :)
There is a slight inconvenience in that the ISS has 6 bedrooms and 7 astronauts, so now one of them will be sleeping on the couch for 8 months rather than 8 days.
Wonder what that actually translates to, in space
Is there an extra "guest" specially-adapted "zero gravity sleeping bag" or such?
If they decide to go with the plan of sending a reduced crew in Crew-9, they'll probably add extra supplies to that too. So, supply wise there shouldn't be any concerns.
Not sure, but a Cygnus resupply mission (NG-21) launched on the 4th of August, so I'm sure they have plenty of supplies.