if you want to have the broody hen raise the chicks in the flock, you have to leave her there. I only separate my layers out of the coop for about 12 hours, until everything has hatched that is going to hatch. The vunerable time in my opinion is when the first chicks have dried off and get adventurous, and leave the nest, and mama is not quite ready to leave the chicks still hatching. But once everyone has dried off, the broody hen generally leaves her nest, and creates a new nest on on the floor of the coop with the live chicks.
By leaving the broody hen with the flock, she remains part of the flock and rather high on the pecking order, cause mine are crabbier than a bear, and the layers tiptoe in, and try not to upset her. So once she gets them hatched, her hormones are running high, she is highly defensive of the new chicks, and the new chicks instinctively remain rather close to her. If one strays off, a layer reminds them where they belong, mama comes running to the rescue, and order prevails. The chicks quickly learn to keep out of the way of the layers with mama between them, as the hormones decrease, and the chicks get bigger, the layers are used to them, and while will still give a peck, are fairly accepting.
When you separate the hen from the flock, she loses her pecking order place, and when you wait for a couple of weeks she is like a new bird being added. Now her hormones have started to fade, and now she must protect her own interests and try and find her place in the flock again, generally leaving the chicks to fend for themselves.
You will probably have to finish raising the chicks yourself, or leave Rose separate with the chicks and reintroduce them all when the chicks are nearly full size.
Mrs K