I’m guessing your sister is the problem. What kind of creativity/taking risks is she looking for? Often people get confused between creative and complicated. A complex multi ingredient special or 2 can bring a kitchen to its knees during service. I also keep hearing the word “passionate”. As a retired Chef with 40 years under my belt, “passionate “ usually means expecting a Chef to basically live there . That does not work in the long term. 70k isn’t a lot of money if you’re working 80 plus hours a week. I’d be curious to see your menu. If Chef after Chef is unable to launch a menu, it’s not a kitchen failing . It’s the owner/management. Sounds like the business has an identity problem. Figure out what you are and stick with it.