She may or she may not.
Best to add them at night so she doesn't see you do it.
Watch her carefully in the morning, as you don't want her pecking them when they come out to eat/drink.
Make sure you have the feeder and waterer very close by so the chicks don't have to wander far, since they will be thirsty and hungry NOW, whereas the newly born chicks can go a couple days fine without food/water since they will be digesting the egg yolk. You don't want the day olds to get hungry/thirsty.
Only add brand new chicks that were just shipped in to the feed store- not week olds or anything like that I have read.
I have successfully done this once and unsuccessfully done it a couple of times.