Hey @dccc,
The grouping feature will take the features of the two lights and combine them to use the features that they have in common; unfortunately, I do not believe that this extends to some of the advanced scheduling features such as Away Mode.
These features and schedules are stored on the plugs themselves, while the group feature is a feature that comes with the devices being connected to the cloud.
Your best bet would be to create a Smart Action at specific times if you want them to operate in tandem.
I would recommend creating a feature request to allow for increased control / pairing of grouped devices. With the addition of local smart actions via the hub, this is something that could be considered or looked at to see if it could be added.