Writers are taught to "get the most mileage from the material they research and write. When we write a book, can we write others in the same vein or related to it? You'll even find this in the children's book writing field.
When I discovered the children's story book, The Quiltmaker's Gift, I didn't realize there were related books with quilt patterns and suggestions. In researching an answer for a reader's question about this book, I discovered more and wrote about them in Follow-up Books for the Quiltmaker's Gift.
You may want to check out these books:
The Quiltmaker's Gift
Quilts From the Quiltmaker's Gift
More Quilts From the Quiltmaker's Gift
How can you expand upon the books you write, whether they're for children or adults, fiction or non-fiction. Put on your thinking cap!