How do we add flavor to yogurt such as adding peach jam?
The best time to do this is after the fermentation is completed and before the fridge stage.
Then the yogurt will be broken as we mix it with jam. Is it going to reform during the fridge stage?
Yes, this is what it should happen when you mix authentically made yogurt with whatever else.
This is precisely the reason for the creamy texture of the commercial yogurt.
To get a commercial result you should follow the commercial method of making