I have a couple of my snakes that have refused larger prey than adult mice, but will readily chow down on 2-3 mice per feeding (my 3 yr old albino ball in particular). You could start with one prey item for the first few feedings, then try offering 2 for a few feedings, then up to 3 if they will take it. I prefer a larger prey item per animal, as I feel the larger more developed bone and muscle structure is beneficial and more filling (my opinion only), but I will cater to a preference if the snakes refuses too many meals in a row. That said, I’ve only rarely had babies that wouldn’t switch to larger prey as they got older.