Three things: isn’t this for the new business owner to sort out, at their cost? And if the person working for $10 is a resident would the activity not be covered under your general insurance? A simple check with the insurer would confirm such. And getting an ABN is a pretty standard free thing and very easy to get, so they should just register to get one. But for a tiny $120 a year in income that might be swallowed up in end of year extra accounting fees to keep the ATO on-side.
As I understand it:
Strata insurance usually provides cover for volunteer/unpaid workers. Once you start paying them they become employees or contractors.
For employees you would require workers compensation coverage.
Public liability insurance policies usually require that anyone operating a business within the insured premises has their own PL coverage.
Perhaps the tenant could “volunteer” to do the work, but receive “reimbursement for expenses” from the OC?