Selkies' Skins: Castle and Well

Selkies are Scottish seal people, and are considered magical shapeshifting creatures, able to interbreed with humans. Spoken of in many old stories, the females are said to make caring wives, and the men to be charming and good lovers. If their skin is captured, they will remain on land, though more is heard about women being captured than the men. If they find their stolen skin, they will return to the sea and any mate or family therein, though remaining nearby to watch over their land-children.
What happens though, if a Selkie never manages to reclaim her skin before her death, and so remains with her children? What happens if her family is a magical one, and her subspecies had been created by the cooperation of sister water goddesses? Further, what if the drive to return to the sea remains strong in the offspring, and as servants of these goddesses, provide their care despite being disliked and untrusted by both full blooded Selkies and humans when found out.
We come then to modern times. First a fishing family, favored then by fortune and Marsali's magic, the Makay clan grew to a merchant family that went on grand voyages for the good of the Magical Community. Few now remain, and those are now waterwitches, primarily interested in tending duties set by deities that few believe actually exist, and the health of the waters both locally and planet wide.
Kirsty has little choice in her fate, only how it will manifest. There are tests to pass, a place that she may have to occupy prematurely if her visions prove true, and a need to earn her sealskin to be complete. Will Etain return safe to port, and will Kirsty survive her training and test? There are complications along the way, will she be able to stay on the course she's trying to set? In this first book of what is intended to be a trilogy Kirsty must ultimately go down the Lady's well for the first of her tests of fitness, while also having to balance school, family, and a certain lad.