Like I mentioned in the instructions, don't stress about measurements. They really don't matter! Use more fruit, or use none at all. They will still be delicious.
You can use plain whole milk Greek yogurt. But, older toddlers, kids, and adults might have a hard time with the sour flavor. Babies will love it!
For babies 6-12 months old, omit fruit as this could be a choking hazard.
Feel free to add other mix ins like chia seeds, nut butters, honey (12m+), and more!