I suggest you mark the eggs you want her to hatch and check under her at the end of the day to remove any new eggs. These eggs are good to use.
If an egg does not have bacteria there is nothing technically wrong with it, even if it has been under a broody for a while. Even if it started to develop, as long as it has not gone bad and started to smell, you can eat them. Personally, I don't.
From Wikipedia - The pictures show that it is well developed.
A balut is a fertilized duck embryo that is boiled alive and eaten in the shell.
Popularly believed to be an aphrodisiac and considered a high-protein, hearty snack, balut are mostly sold by street vendors in the regions where they are available. It is commonly sold as streetfood in the Philippines. They are common, everyday food in countries on Southeast Asia, such as Laos (where it is called kai luk - ໄຂ່ລູກ), Thailand (khai khao - ไข่ข้าว in Thai), Cambodia (pong tea khon ពងទាកូន in Cambodian)[1] and Vietnam (trứng vịt lộn or hột vịt lộn in Vietnamese).
