Sure, they may not be nuclear, but Dicey and her siblings are a family nonetheless. They've just come to live with Gram, and they’re anxiously awaiting the day when she adopts them and it's all nice and official. Dicey’s outside working on the boat in the first chapter, which tells us that she’s solitary and an adventurer. When Gram comes in and tells Dicey to put on a shirt, we see that Dicey is growing up. So right off the bat we know that Dicey's seen some tough times, and she's growing up, so we're betting she'll see some more soon enough.
The entire middle of the book is majorly complicated, as life tends to be when you’re thirteen. Add poverty, a whackadoo grandmother, a mom in a mental hospital, a sister who can’t read, and teachers who don’t get it, and it’s safe to say nobody’s life is easy in Dicey’s family.
Then there’s the whole trouble-making-friends thing, in which Dicey struggles to learn how to reach out, hold on, and let go to other people all at the same time. Waiting for Gram to adopt them is perhaps the biggest complication of all; until the papers come through, the Tillerman siblings are afraid of winding up homeless again.
A lot of people take their first plane ride to go on vacation, but not Dicey: she’s going to visit her dying mother in the hospital in Boston. What, you thought Dicey and Gram were going to catch a break?
Momma’s death is the point at which Dicey realizes things have changed for good; there’s no hope that they’ll all be reunited at Gram’s house. It’s not only incredibly sad, it’s the ultimate lesson in letting go.
When Dicey and her siblings bury Momma under the mulberry tree in Gram’s front yard, you can see that they’re all beginning to come to terms with the fact that she’s no longer with them. Dicey stands over her grave and says, "Home and gone," because she’s finally realized a person can be both at the same time.
Dicey’s Song ends with Gram bringing photo albums down from the attic, as well as finally giving the kids permission to go up there and explore. They all gather in the living room, and Gram shows them pictures of their mother and her two brothers (one of which is named Bullet, for real). Not only do we see the kids beginning to feel like they’re part of a family at last, Voigt leaves the story open-ended, which sets up the sequel quite nicely.