S. A Bodeen

After his parents, two sisters, and he have spent six years in a vast underground compound built by his wealthy father to protect them from a nuclear holocaust, fifteen-year-old Eli, whose twin brother and grandmother were left behind, discovers that his father has perpetrated a monstrous hoax on them all.

Shipwreck Island, Book 1:
Sarah Robinson is deeply troubled in the wake of her dad's second marriage. She now has to deal with a new stepmom and two stepbrothers, Marco, who is her age, and Nacho, who's younger. Even though they've all moved from Texas to California to start life as a new, blended family, none of the kids seem remotely happy about it.
Sarah's dad and stepmom then decide to take the whole family on a special vacation

...

Sarah Robinson and her family are shipwrecked on a remote and mysterious island. Their food is running out, and their fear is escalating as there is no sign of rescue. The mysterious girl they found unconscious at the beach is healing, and what she tells them about the strange island and especially about someone called the Keeper has the family on edge. When Sarah's dad and Marco's younger brother go missing, the mystery becomes dangerous. Now, it's...

Sarah Robinson still can't believe her dad has remarried. Now she has to deal with a new stepmom and two stepbrothers, Marco, who is her age, and Nacho, who's younger. They've moved from Texas to California to start life as a new, blended family. But none of the kids seem happy about it. Sarah's dad and stepmom decide to take the whole family on a special vacation so they can get to know each other. They'll fly to Fiji, charter a boat, and sail for...

Sarah Robinson and her family are shipwrecked on a remote and mysterious island. Their food is scarce and there's no sign of rescue. They have seen strange creatures, rescued a mysterious girl, and found the Curator, who has captured Sarah's father and stepbrother to use in a bizarre time travel experiment. And then the only man who knows about their island comes back-he's looking for buried treasure, and won't leave without it, even if it means leaving...

When a young Tanzanian girl gets a new baby brother, she finds a rock, which she names Eva, and makes it her baby doll.

When her mother has a new baby, Elizabeti is given charge of her younger brother and finds it more difficult to take care him than it was to care for her rock doll.

When high school sophomore Mason finds a beautiful but catatonic girl in the nursing home where his mother works, the discovery leads him to revelations about a series of disturbing human experiments that have a connection to his own life.