Aww, the taste thing is so real! A few of us went through this din, and honestly what worked was mixing it gradually, start by putting like 3/4 Pediasure 1-3 with 1/4 Pediasure Plus, then slowly adjust the ratio over a week or two so they don't notice the difference as much. One of my mum friends also tried mixing it with a bit of banana or strawberry to mask the taste, and her son drank it better that way!