I'm in the exact same boat as you. Our broody's eggs hatched July 2 and I decided to let her raise her chicks in the coop too. Keeping the other hens (we have 3 other plus our momma hen) out of the chicks' water isn't much of a problem. Keeping them out of the chick feed is the problem. And while trying to get to the food they do tend to repeatedly knock the chicks' waterer over. It's tough - no question about it. I've started to just let momma hen and her 8 chicks out in the yard all day to free range. I put their feeder and waterer on the ground and they can get either when they want. Momma hen does a great job of protecting the chicks. They are 1.5 weeks old today and all are thriving. The other 3 hens I just leave in the coop/run and give them treats about twice a day and they don't seem to mind having to stay fenced in. I do end up letting the hens out in the evening to free range for a couple hours too. But the first thing they'll do is head straight for the chicks' feed!!!
I'm eager to hear better ideas, as I'm sure there are some...just haven't put the time into thinking of one yet.