CLEVELAND - With her beloved Cleveland Indians looking to clinch their first World Series title since 1948 on Tuesday, Laurie Green couldn’t think of anybody better with whom to share her seats than a Chicago Cubs fan.

After all, she’s the sister Green had never met.

Green, a season-ticket holder who works in education services for a PBS station in northeast Ohio, was adopted as a baby in the early 1960s. She tracked down her biological father three years ago after extensive research and has developed an online relationship with his only daughter, Selena Brosnan.

After repeated attempts to meet in person, the sisters were finally brought together by the game they love.

“Laurie had the ticket and invited me,’’ said Brosnan, 40, a Montessori teacher in Chicago. “We’ve tried to get together in the past but the timing didn’t work out. In the frenzy and excitement of both teams making the World Series, this was the perfect opportunity.’’

This was the first time Brosnan, who has lost track of how many games she has attended at Wrigley Field, got to watch one at Progressive Field. And it was a game with historic implications, considering the clubs hold the longest championship droughts in the majors.

PHOTOS | 2016 World Series, Chicago v. Cleveland

The sisters were much too happy about finally meeting – they even asked a fellow passenger on the train ride to the ballpark if they look alike – to mind sitting alongside a fan of the opposite team.

“The fact both our teams are in the playoffs is so exciting,’’ said Green, 54. “I’ll be happy if they win – don’t tell my friends – and she’ll be happy if we win, I’m sure.’’

Their gathering has come about thanks to Green’s dogged efforts to reach out to her biological father, Ralph Monical, who lives in Chicago. The oldest of her three daughters, Kelly, had physical and psychological issues as a child, so Green decided to seek genetic information that might help in addressing them.

Green was born in Palos Verdes, Calif., and given up for adoption when she was six weeks old. Her mother, whom Green has never met, never notified Monical of his daughter’s birth. She also misspelled his last name as “Montical’’ in the birth certificate.

With her adoption records closed, Green faced an uphill climb in locating her father. It wasn’t until the advent of more sophisticated search technology that she managed to find him through Ancestry.com.

After sorting through the shock of the news and getting DNA confirmation, Monical and his family – which includes three grown sons – have been welcoming of Green. Brosnan was enthused.

“It was surreal because I only have brothers and I always wanted a sister growing up,’’ she said. “It’s kind of strange to think I went from this very male household to, ‘I have a sister. I wonder what we have in common.’ And then I find out we have quite a bit in common.’’

Such as a passion for baseball. Green’s was handed down from her adoptive mother, who grew up in Cleveland’s west side during the Depression. After Green’s parents decided to return to their native Ohio when she was 18, her love of the Indians developed.

Green cried while Brosnan cheered during the Cubs’ three-run first inning in Game 6, and she dearly missed her mother, who passed away three years ago.

“I know she would have wanted to be here to see them win,’’ Green said. “In 1997, I was pregnant with Dana, my 18-year-old, and I remember pounding the ground in our living room when Jose Mesa gave up that hit between first and second (blowing the save in Game 7 of the World Series, which the Indians lost in 11 innings).

“My mother was beside herself. ‘Laurie, you’re going to go into labor. Stop it! Stop it!’’ My mother wanted more than anything before she died to see the Indians win, so this is for her.’’