I would take them together. They'll be a comfort to one another, and this could help to speed up the recovery process. I take Trav in at around 8:15am, they're settled in, fed and watered up to the op. The amount of GA used is minimal, as it's not usually a too long or intense procedure (unlike a spey for example).
I usually call them around 2pm to see how it's gone, and by this point he's usually ready to come home.
I send them of with a pack up for the day. Usually a little veg and some pellets to check he's eating OK.
A dental should not cause discomfort or pain. The teeth are burred down (similar to filing your nails). Therefore, the only thing that should need recovering from is the GA - and possibly feeling a little stiff from them opening the mouth so much.
Therefore, it shouldn't be too much of a disruption to their normal way of life.
The first dental, I would possibly keep them in for one night just so that you can keep an eye on them and monitor how quick the recovery period is. This way you know for future reference.
The only time I've had to change the food I've given is when Trav's had to have a tooth extracted. This has often meant that I've had to grate up his veg for a few days.
If she appears to be a bit bruised or tender, then you can grate up veg and either soak the pellets or use a pestle and mortar to grind them up.
If this is still a problem after 24 - 36 hours, I would take her back to the vets.
Hope it all goes OK for you.