I have a broody hen at present with a single chick. In answer to a couple of questions, generally speaking, no matter the rank of a broody, no one likes to mess with a broody hen.
I had the luxury of an unused coop section with its own exterior run, and it so happened that coop was where the broody chose to sit a nest where I then slipped a few fertilized eggs under her. It worked out beautifully when the one egg hatched and the broody and new chick were safe and secure from the flock which comprises all ages.
When the chick was around two weeks old, I opened access from the broody's run to the rest of the run so all the flock could mingle and the broody could begin integrating her chick with the flock. No one messed with the chick. The chick is six weeks old now, and still no one messes with her except for very rare games of tag and peck by the very youngest pullets, usually provoked by the adventurous chick.
But the broody, even though she was very high ranking, has had to engage in challenges from others as she re-enters the social order after being out of it for a couple of months. These are not altercations where she's protecting her chick but direct challenges to her alone. The challenges are brief, and no one gets hurt, but there's no doubt what they're about. So I will guess your broody may encounter such challenges to her rank as she re-enters the pecking order.