Book illustrator Krystal Kramer said Amanda wrote the book based on her experiences as a mother.
"Raising her six children showed her something profoundly different—that we are born good," Kramer said.
Online posts from two years ago under the username "MandyK1179" detailed marital struggles and infidelity. Amanda expressed fear about leaving due to raising six children while navigating counseling.
Family members released statements grieving the loss.
Amanda's parents, Steve and Becky Lawwill, said, "We treasured every moment we had with her and her six children, and words cannot adequately express our devastation."
Her cousin, Emily Jones, highlighted Amanda's dedication to her children and a recent trip to China with her adopted daughters.
Grand Haven Area Public Schools is offering counseling support.
Superintendent Kristin Perkowski said, "Our hearts are with their family, friends, neighbors, and all who knew and loved them."
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The Ottawa County Sheriff's Office asks anyone with information to contact investigators.