To substitute baking powder for baking soda, you must adjust the measurement because baking powder is less potent. The standard ratio is three parts baking powder for one part baking soda. Regarding your yogurt, it provides acidity that normally reacts with baking soda to create carbon dioxide. Baking powder already contains an acid component, so the yogurt is not strictly necessary for the leavening agent to work, but it adds wonderful moisture and flavor to banana bread. Mix the baking powder with the dry ingredients evenly, combine with your wet ingredients including the yogurt, and you can proceed with your meal prep without worrying about ruining the texture.