From what I've read on this board.....
Depending on what kind of hen has gone broody, she can sit and raise between 6 and 18 eggs. How long has she been sitting the "unauthorized" eggs?
One option is to let her sit on her original eggs until day 16 or so, incubate the purchased ones up to that same point and then swap them around. She ends up hatching out the "authorized eggs", and you hatch out in the incubator the "unauthorized" ones.
You can swap them out now as well, and let nature take it's course. Choice is yours.
Watch for when Mama gets off the nest to eat, and swap out the eggs in the nest for the ones you want her to sit. Make sure she doesn't see you messing around the nest, or she may come running back and refuse to accept the new eggs. She still might reject the new eggs, because they don't smell right, but it's worth a try. Just make sure you bring the "authorized eggs" up to room temp or slightly warmer.
I found out the hard way, that after hatched-out day two, the hen won't accept any new chicks, and have ended up raising three chicks by hand in the house.
Good Luck!!
Kathy
