In her book Behind the Shoulder Pads, the Seven Thieves actress, 90, revealed her sister Jackie chose not to attend the nuptials, which took place on 17 February 2002. She explained novelist Jackie's relationship with her former boyfriends and husbands had been strained, with Joan admitting her sister threatened that she'd "never speak to me again" if she married Peter Holm.
"Jackie hated my fourth husband, the Swede, Peter, and told me she'd 'never speak to me again' if I married him. As it turns out, she was quite right, because I divorced him a year later.
"Similarly, we went through a period of coolness later when I was seeing my English boyfriend Robin, who was often sarcastically rude to her, correcting her pronunciation and commenting on her taste. Maybe that explains why she didn't attend my wedding with my now-husband, Percy," she wrote.
Joan revealed they managed to repair their relationship, and Jackie and Percy eventually developed a bond.
"But Jackie and I never confronted each other about our problems, and it was only when I married Percy and she grew to love him that our rift finally healed," continued Joan, who was left "bereft" following Jackie's death in 2015.
When Hollywood icon Joan met company manager Percy in 2000, she had no intention of getting married again.
Their love story began when Joan was starring in a play for a company Gibson managed in San Fransisco. Recalling their first meeting, she told the Mail: "We hit it off immediately. He was funny, engaging, good-looking, and after the show I would socialize with him, my costar George Hamilton and my daughter Katy."
The couple decided "life was short" following the tragic events of 9/11, prompting them to marry in London in front of A-list stars including Dame Shirley Bassey, Roger Moore and Rupert Everett.
Photos show Joan swerved the classic bridal white wedding dress for an unusual lilac mermaid gown with a bateau V-neck and dramatic lace-trimmed sleeves by Dynasty costumier Nolan Miller.
The bride added pastel purple shoes by Manolo Blahnik and a matching headpiece, while Percy looked dapper in a Scottish kilt.
She has since had nothing but praise for her husband, telling HELLO! Magazine in 2015: "It is my fifth marriage, and my happiest, and last.
"Percy is wonderful, he's my soul mate. That doesn't mean we don't bicker but we are very understanding of each other."