In general, yukkuri have low intelligence and they can't remember many things. But seeing it from opposite side, they can clearly remember things that are less. In the smallest family composition, there are things they won't forget.
For that reason, parent yukkuri with many childs can't recognize every individual and sums them up as "Little Ones".
Parent Marisa can at best remember the youngest little one and the eldest Marisa who helps her with hunting.
In the other hand, Reimu type tend to favour Reimu type children, so there are case where they killed their own Marisa type children. It's not that they hate Marisa-type, but it's simply because they are "not alike". There's no evil intention behind it so even when the parent Marisa asked about the killing, they can't understand why they are blamed.