Since my son, Manny, was born four years ago, I've marveled as he's gracefully sailed through developmental milestones, navigating the world with grace, ease and confidence.

Recently, Manny, my husband, Dave, and I were hanging out in a local coffee shop. After our son gobbled down his giant chocolate chip cookie, he noticed his hands were covered in chocolate. He announced that he was going to the bathroom. He took off to the back of the coffee shop, entered the small, single bathroom, washed and dried his hands, then returned to our table.

Dave and I looked at each other and laughed. "Amazing, just amazing," my husband said, shaking his head.

Our son is not our only child. Our daughter, Ella, was our precious first, born in February 2003. Because of an injury caused by her difficult birth, she suffered severe brain damage, causing spastic quadriplegia cerebral palsy. Ella's body was rigid, tight and stiff; voluntary movements of her limbs and head were impossible. Ella was never able to walk, talk or do anything for herself. Her physical disability made her medically fragile. We feared her catching a simple cold, as it could turn into pneumonia within days.

Every day was a struggle for Ella, and I bore witness as she failed to grow and thrive. Each day, I felt like I climbed a mountain just to get over it and on to the next day, only to repeat the same struggles. Feeding, diapering and keeping Ella clean and out of harm's way were my daily tasks for her entire life.

My husband and I poured our hearts and souls into caring for Ella, while giving her as rich and full a life as possible. She attended school and community gatherings and had many friends. We traveled the world. She swam with dolphins. Dave and I created and built a ski sled that we pulled behind us while we skied so Ella could enjoy the winter, and we designed a safety harness system for our paddleboards so she could experience being on the lake in the summer.

For our own sanity and survival, Dave and I learned to reframe our expectations of our daughter and ourselves. By necessity, we learned patience. When your child fails to reach milestones year after year, there's a desperate need to recognize and celebrate any forward momentum as time passes mercilessly by. We cheered and cried over Ella's first smile at age 2 in a hotel in Montréal. While on vacation in Ocean City, Md., 3-year-old Ella made her first reactive sound. I was cooking and hit a spoon against the side of a pot. The high-pitched noise made Ella moan, a delightful sound accompanied by a slight smirk. The more I did it, the more she moaned. We quickly called our families so they could listen to her.

When, at age 7, she hit the yes/no switch on her communication system at school for the first time, the whole school — students and teachers — celebrated Ella with high fives. With each passing year I celebrated Ella's birthday with as much vigor as I could muster, planning elaborate parties knowing full well that it would be another year of missed developmental milestones.

Ella graced our family for 11 years. After a long year battling pneumonia and very low red blood cell and platelet counts, which put her in and out of the hospital for weeks at a time, Ella died. She passed at 4:30 p.m. on a beautiful Sunday afternoon, Mother's Day 2014. She was ready. She was tired. She was peaceful. Ella's last breath broke our hearts, crushed our souls and released us from the incredible task of caring for her every need, every single day of her life.

Three months after Ella died, Dave and I took a healing journey, driving across the country, then flying to Hawaii for a few weeks. On our way back to Vermont, I fell ill in a hotel in Flagstaff, Ariz. I took a pregnancy test, and it was positive.

In May 2015 — a year and five days after Ella died — I gave birth to a beautiful, healthy baby boy, Emanuel Blessing. Manny.

He is the embodiment of the strength of our marriage — full of love, joy, grit and determination. He has his sister's sweet smile and the same wild, untamable head of curly blond locks. He is love.

My husband and I channel the unconditional love we learned from Ella to Manny. He inspires us with his lust for life and we indulge his obsessions with dinosaurs, monster trucks and Katy Perry.

This time around, parenting is different: easier because of Manny's abilities; harder because of his strong will; and painful, at times, as I think back to how hard everything was for Ella and how much we miss her.

I have a not-so-helpful tendency to play the "What if" game regarding Ella's life. What if her birth injury never happened? What if I worked a little harder on her speech therapy and her occupational or physical therapy? What if she were still alive to meet her little brother?

The "what ifs" crept in as I watched Manny speak his first word, take his first step, run down a hill, potty train, learn to ride a bike and wash his hands, get dressed and eat breakfast all by himself. I feel sadness and guilt that Ella never got to do those things in her life.

However, it doesn't take long before I'm jolted back to the present. I'd like to think that's Ella, sending me a shock from beyond, telling me to enjoy and witness the divine human growing right in front of my eyes.

Ella had a sage-like quality — quiet, wise and knowing. There was always a lesson to learn in her presence. When she was alive, there was no choice but to stay present. Her past birth injury was far too painful to dwell on and her future too uncertain. So staying in the moment was the only way for me to find joy in my role as her caregiver.

When Ella made small gains in her development, they felt huge to us. As a result, Manny's monumental milestones feel magical. If not for our daughter, I may have missed the magic. It's Ella I have to thank for waking me up to the miracle of the present.