IANA should be able to obtain access to a COVID-19 test.
Before they isolate themselves, have the participants tested and confirmed virus free, THEN lock them in together.
People living in the same household aren't held to the social distancing requirements...that'd be daft. Being locked in together for a few days would hold the same strictures, I assume. And if they've been tested and confirmed virus free the point should be moot, regardless.