I have had one that is acting a little broody-ish. But then she hops off the nest and acts normal for a while? I don't get it. Anyway, while she was on the nest she was covering 10 eggs with no problems. I think she could easily handle a dozen, and maybe even up to 14. If they were bantam eggs, and she is a large hen (being a buff orpington, she should be! lol) she could easily handle 16 bantam eggs, and 12-14 regular sized eggs. Good luck with her! And please cross your fingers that mine gets a little more serious! LOL
I breed minature silkies (I call them minature becuase they are smaller than bantams)
and right now I have one sitting on ten eggs!!! If a tiny Minature silkie can hatch that many, imagine a Buff Orpington!!! Thier secret is to puff up thier feathers.