Ben Affleck and Jennifer Garner's child uses new name in public for first time at grandfather's funeral

The child of Ben Affleck and Jennifer Garner has used their new name publicly for the first time.

The couple's middle child introduced their new name while giving a reading at their grandfather's funeral on Saturday (6 April).

Jennifer Garner's father William Garner passed away recently at the age of 85, with the 13 Going On 30 star paying tribute to him in an emotional post to Instagram.

"My dad passed peacefully Saturday afternoon," she wrote. "We were with him, singing Amazing Grace as he left us (did we carry him across or scare him away – valid question).

"While there is no tragedy in the death of an 85 year old man who lived a healthy, wonderful life, I know grief is unavoidable, waiting around unexpected corners. Today is for gratitude."

She added: "We are grateful for Dad’s gentle demeanor and quiet strength. For how he teased with a mischievous smile, and for the way he invented the role of all in, ever patient girl dad. We are grateful for his work ethic, leadership and faith."

William's memorial service at the Christ Church United Methodist in Charleston, West Virginia was live streamed on Facebook, which saw Jennifer and Affleck's child - who recently started using gender-neutral pronouns - step up to the podium wearing a black suit and tie and a buzzcut.

Introducing themselves to the gathered congregation, they introduced themselves with their chosen name, saying: "Hello my name is Fin Affleck."

Fin then gave a reading from Chapter 16 Verse 8 from the Book of Proverbs, reading: "Better is a little with righteousness, than a large income with injustice."

Their siblings Violet and Samuel joined them, standing in front of Fin as they gave the reading.

Each relative took a turn to read from the Book of Proverbs, which was a favourite of their grandfathers.

Jennifer continued her tribute to her dad online, thanking the medics who had cared for him during his passing.

She wrote: "We extend our gratitude to the medical communities of Charleston Area Medical Center and City of Hope.

"Your care extended Dad's life and gave him time to be in his favorite spots – surrounded by daughters and grandchildren, cheering for his beloved Aggies, captaining a boat, and – most of all – next to his wife of 59 years, our Mom."

Jennifer concluded the tribute by writing: "There is so much to say about my dad – my sisters and I will never be done talking about how wonderful he was, so bear with us – but for today I share these memories with my appreciation for the kind and brilliant man, father, and grandfather he was, as well as the loving legacy he left behind."