to be honest, you are the boss, you can say no to anything that you don't like. She is just an assistant, that's all. don't let her do thing her way. remember, you pay her, she didn't pay you.
don't set up bad sample and you can't correct it later. if you think it's not necessary to eat that much 花膠 a day, cut it down. just tell her, it's your choice. Be careful, some ppl told me they make you buy expensive stuff and cook alot, so they can have a share too when you can't finish it. be careful.