They met in a Bible study class. He proposed at a Barnes & Noble bookstore, kneeling in the aisle with a ring concealed behind a magazine. They married, had a girl, then a boy, and figured their family was complete.

That's when the storybook ended and the real story began.

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Gavin was born at 30 weeks - a morsel of a baby, weighing just over 3 pounds. His body temperature fluctuated; he wasn't gaining weight; he was prone to infection. At first, Karen and Adam thought his struggles were due to prematurity. But after 18 months of hospital stays and countless medical tests, they got a diagnosis: mitochondrial disease, a rare and profoundly debilitating illness in which cells generate less and less energy.

For three years, the family, including 2-year-old Maddie, essentially lived at Nemours/Alfred I. duPont Hospital for Children and the Ronald McDonald House across the street. Each morning, Adam would drop Maddie off with Karen, then drive an hour to Plymouth Meeting, where he worked for Aetna.

The couple had brought items from home to make the hospital room more inviting: a table lamp, their iMac, pillows, toys. Karen took Maddie on long walks through the hospital. They ate cafeteria food for dinner. And they became fluent in a kind of parenting that wasn't in any of the books: a language of feeding tubes and ostomy bags, ventilators and IV lines, panic and reprieve.

They learned to find joy in small moments: a smile from Gavin, a goofy game of bowling in the hospital corridor with Maddie and a set of plastic pins. They learned how to love a child who was not going to live.

And when Gavin died, on a chilly November day in 2009 - 52 agonizing hours after Karen and Adam decided, finally, to disconnect his life-support systems - they felt both shredded and relieved. "I vividly remember walking out of those hospital doors, thinking, 'What is next? How do we even live a normal life?' " Karen recalls.

The couple wanted to use what Gavin had taught them. So they began learning about adoption and the thousands of medically fragile children in need of homes. One day, Karen was browsing Pennsylvania's adoption website and read about a toddler named Angela, who had cortical blindness and cerebral palsy. "She looked a mess - this little, tiny girl. I thought: We could do so much with her. I completely fell in love."

Adam remembers meeting Angela for the first time; he sat on the couch in a foster home in Chester, trembling with tears. "I was so excited to hold her and know she was going to be part of our family."

Angela had been home only a month when the couple first glimpsed Jayden, featured on a "Wednesday's Child" spot on NBC10. The boy was living in a medical facility; he had suffered brain damage from being shaken as a baby. He wore a padded helmet and took medication to prevent seizures.

Karen looked at Adam, pointed to the television and said, "That's him. That's our next placement." Jayden, they learned, had already been matched with a family. But Karen couldn't let go; she called the adoption recruiter regularly and obsessively re-read Jayden's profile on the state website. Months passed. Then the adoption worker called.

"Are you sitting down?" she asked Karen. "The other family fell through, and they want you guys for Jayden." They began to visit and bond with him, this introverted toddler who had a tracheostomy to breathe, whose anti-seizure medication and sedatives dulled his personality. He came home in February 2011.

Once again, the family felt complete. Jayden, once weaned off some of his medications, became alert and curious. Angela learned to use a walker and mastered some basic sign language. Maddie played unself-consciously with her sister and brother, dressing up with Angela, tumbling with Jayden.

Karen and Adam watched their kids - all their kids - thriving. So when the adoption agency called in 2013 to tell them about a little girl with some "minor medical issues" - she had a feeding tube and was a failure-to-thrive baby - they couldn't say no. They brought Harper home that spring.

For some, that might have been more than enough: a family of one typical kid and three with significant medical needs. A family that requires a wheelchair-accessible van, an emergency trach bag, feeding pumps, and a supply of oxygen for a one-day trip to the beach.

"On paper, we look a mess," Adam says. "You think: How does this work? How does this family even function?" That may be what adoption workers were wondering when the couple contacted them once more, about a 9-year-old boy whose profile they'd spotted on "Wednesday's Child." He had a trach tube, like Jayden, and cerebral palsy, like Angela. "We knew we had to go and give this kid a home," Karen says.

Soon they will head to the courtroom in Lancaster County for what they vow will be the final time. Karen and Adam will declare, under oath, that they will care for this newest child as if he were their biological son. Adam will choke up when he pledges, "I will."

Back at home, they note miracles that come in the tiniest increments: Angela sits up on her own for 10 seconds. Jayden, who doesn't speak, uses the iPad to tap out his needs: "I want. To play." Karen says, "To see our children smiling and thriving and beating odds is amazing."

They think about Gavin every day, and especially on certain occasions: Mother's Day. The day they signed his DNR. And each June 14, when they bring a cake to his grave site, sing "Happy Birthday" and release a clutch of helium balloons.

It's not a perfect story, but it is a true one: The boy who lived, and died, and changed his parents. The child who cracked their hearts open, making room for more.

The Parent Trip

If you've become a parent - for the first, second or fifth time - within the last six months, e-mail us why we should feature your story:

(Giving birth, adopting, or becoming a stepparent or guardian all count.) Unfortunately, we can't respond individually to all submissions. If your story is chosen, you will be contacted.EndText