Ducks and their eggs

We have a duck at work that has laid her eggs under a Bush, which is open to all potential threats.
She is sitting on the eggs most of the time and we have cordoned the area off so that people can't go near. The male duck comes and goes. We feed her specialist duck food. There is another duck couple who come and sit by her whilst she is sitting on her eggs. Are the other ducks there as a support or is there another reason why they spend time there? What can we do once the ducklings hatch to protect then from potential threats - larger birds, foxes, etc.

Sadly, if its a wild duck, there's nothing you *can* do.