关于GroupSave

网站上说：With GroupSave 3 or 4 people can travel together Off-Peak by train for the price of 2 adults to hundreds of destinations in the London and South East area.


我和父母一共3个人 可以使用 GroupSave么？ 上面的意思应该说3个人就可以的了。

不过为啥http://www.daysoutguide.co.uk/london-to-bath-groupsave

上又只显示

GroupSave pp when 4 travel together: £24.00


那就是3个人能不能用GroupSave啊