If you have more than one of the same component in an assembly drawing then you can redistribute the balloon quantity and add balloons for more instances of that part.
If you are calling out the same component more times than the quantity in your BOM, then you'll have to add a custom balloon symbol that matches your balloon scheme. It's usually frowned on to do this as the number of balloons is usually an indicator of quantity...hence the reference balloon. Furthermore, if the number changes in the BOM structure your symbol won't update.