Back in April, Ali reached out to the "Shake It Off" singer, 26, about the death of her and Max's mother in a touching letter, telling Swift how her brother had wed his wife in the hospital so their mom wouldn't miss out on one of the biggest days of her son's life.
Max and his late mother even danced to the newly single singer's hit "Blank Space" for their mother and son dance before she passed away.
"REMEMBER WHEN TAYLOR SWIFT CRASHED MY SISTER'S WEDDING," Kenya's sister Ashley excitedly tweeted.
"So @taylorswift13 just came to my cousins wedding," another fan captioned a fun selfie with the singer.
Swift also made a special card for the married couple, writing "So it's gonna be forever" in watercolors with a floral circle.
Singer and Smith got married on Saturday at the Brant Beach Yacht Club in Brant Beach, New Jersey.