When Erin McGregor and Terry Kavanagh planned their long-awaited dream wedding, their son Harry was at the center of every detail.

Erin, 43 – the sister of Irish MMA fighter Conor McGregor – and singer-songwriter Kavanagh, 47, were married at the Cashel Palace Hotel in Tipperary, Ireland, on Saturday, August 17. From choosing the venue to organising the ceremony, the couple made many considered decisions, taking into account the needs and wellbeing of 8-year-old Harry, who is autistic.

The PEOPLE Puzzler crossword puzzle is here! How fast can you solve it? Play now!

While they visited and toured more than 20 different venues in Ireland, Italy and Portugal with their planner Andrea Winckworth of Andrea Winckworth Events, they finally settled on the Cashel Palace Hotel. Ultimately, Erin says, they decided that “home is where the heart is” and that getting married locally in Ireland would be ideal for Harry.

“Everyone asks why we didn’t get married abroad. The truth is, it was more important to us that our son was there that day,” Erin tells PEOPLE.

“Our absolute must for the wedding was to ensure Harry was as comfortable as possible and was able to enjoy the wedding festivities,” she adds. “To achieve this, we put in place a number of measures to maximise his comfort and enjoyment.”

These measures included creating a special sensory-friendly environment in his room at the venue with the help of SENCO Sensory Solutions. “This gave him a place to go when he needed a break and he could relax and recharge,” explains Erin.

The couple also held their wedding ceremony outdoors “to give Harry the freedom to move around without feeling trapped in an enclosed space.” And knowing that Harry might not feel comfortable joining the other page boys and flower girls during the processional, Terry and Erin found a different but equally special way to include their son in the experience.

“To capture this moment, we recorded a video of Harry walking up the aisle with us during rehearsal and played it on two TV screens during the ceremony,” explains Erin. “This way we could share this treasured moment with all of our guests, no matter what the circumstances of the day.”

Throughout the wedding weekend, Harry had his “trusty companion” by his side for comfort and security – his therapy dog, an Irish Doodle named Kennedy. In addition, Stewarts Care, a Dublin-based charity for the disabled, brought two therapy ponies to the venue for Harry to ride.

“The therapeutic effect of riding is long-lasting, helps calm his nervous system and brings him joy,” says Erin.

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories.

In addition to Harry, the newlyweds also have 24-year-old Taylor, Erin’s daughter from a previous relationship. To honor both children, the wedding ceremony featured a poignant moment when Terry and Erin mixed pink and blue-colored sand from the location of their first date, Sandymount Beach in Ireland.

“This symbolized the unity of our family,” Erin notes.

The couple also performed a traditional handfasting ceremony, using a colorful ribbon as a nod to the colors of autism. “During this moment, we recited words that expressed our commitment to each other,” the bride recalls.

For Erin and Terry, who first met in Las Vegas when Erin was in town for her brother Conor’s fight, saying “I do” meant “the completion of our family, the final link in our unbreakable chain.”

“It is the fulfillment of a lifelong dream, and the thought of being husband and wife fills us with pride and gratitude,” Erin adds. “For us, it is the ultimate commitment, a promise to love and support each other in every moment that life offers us, and to unite our beautiful family that makes us proud every day into one solid unit.”