Debbie's parents were completely incompetent. They weren't bad people, they were just bad at being people in the modern world. They seemed to always make the wrong decision, and trust the wrong people. Even when it was for the best of reasons. It left them constantly unemployed, broke, running and hiding from unpaid debt collectors and landlords. Debbie got a scholarship to the university and never looked back.
In her junior year she met Henry who was a senior. He was a great guy and they had a lot of fun together. He showed her a whole world that she had never known. The two continued to date after Henry graduated and Henry's family made her feel at home. Heck, they had darn near adopted Debbie into the family before Henry had even proposed to her.
When they were starting out as a young married couple, Henry's parents, Don and Iris, introduced them to all of the people who would help them network. Bankers, investment counselors, insurance agents, realtors ... They helped them find a good school for the kids and schedule great vacations. Basically any and every thing that any newly married couple needed.
Debbie's parents missed the wedding because of a flat tire and the birth of their first child for some other lame reason. Her mom clipped and mailed coupons to her in bunches for products they wouldn't use sold at out-of-town stores. They usually arrived postage due and out-of date.
But Henry's brothers and sisters were welcoming to Debbie as well. With them, Don and Iris, Debbie had the family she never had growing up.
When Henry and Debbie had children, Grandma Iris always came over to thier house to babysit so the infants and toddlers didn't have to travel. "The Grands" were always involved with their grandkids even to the point of specifically inviting the kids to come and "stay over" so that Henry and Debbie could have romantic "date nights" out on the town together.
Harry Chapin sang 'All My Life's a Circle.' And life really is a circle. When you're born you are completely helpless and others take care of all of your needs. Then you enter a stage of life where you learn how to take care of yourself. Then - hopefully - you learn how to take care of others. You get to be the one who actually takes care of others. Finally, not as strong as you used to be - but hopefully wiser and learned - you pass along your accumulated knowledge to those younger while others take care of you.
So when Don and Iris got to the point where their physical limitations threatened to send them into assisted living, Debbie and Henry built an addition onto their house - "Mother-in-law's quarters" the contractors and realtors called it - so "The Grands" could remain independent.