This is very interesting.
I read many moons ago, that an item (that meant a lot to a person) was dipped or dropped into the waters of a holy well for good fortune & healing.
(Much like the later tradition of asking for something & throwing a coin into a well).
So, for young girls, the item used was their toy doll to dip in the water, doing this to communicate with the little folk/pixies/fairies – the idea of the ritual being that they could ask & be granted a wish, such as good luck, or healing for oneself, or for another family member.
Maybe this got changed later to a Friday baptism when Christianity came along ?