Can you roast grapes with sausages?
If, like the sausages, you pierce the skins I can't see why not. If not pierced there is always the chance of an oven cleaning session.
Once had a meal in Holland that was basically Chicken Livers and Grapes casseroled with various herbs and spices. The (white, seedless) grapes made a tasty counterpoint to the Chicken Livers. Should do the same to the herby sausages.