This is a tranquil place in a rural setting with surprising access to the local environs (including Longwood Gardens). The owner/caretaker lives onsite, as mentioned in the listing, and this property is also a retreat center. There is quite a bit of room, here, and while there were just four of us visiting Longwood I imagine it would be roomy for a full complement of nine! Do note it is in an old mill -- the loft staircase is steep and narrow, though the automatic lights relieve many worries. The downstairs bedrooms and bath are particularly nice and have a wide, easy staircase.
The kitchen is very well-appointed, and the coffee the owner set up for us was quite good. If you're planning on cooking a large number of meals and buying supplies all at once I would recommend discussing with the owner in advance, as the refrigerator is shared.
Parking will require care for a larger group, possibly; I doubt nine individual cars would fit (probably should carpool anyway), though with our party two cars fit just fine.