The Twins sequel is finally in development as Triplets, bringing in a third sibling to make up the trio. After 33 years, the sequel is moving forward with director and producer Ivan Reitman back on board with original stars Arnold Schwarzenegger and Danny DeVito. They'll be joined by new star Tracy Morgan to play a third and long-lost sibling to Schwarzenegger and DeVito's characters. The project will be shopped in the Toronto Film Festival Market.

As told by Reitman, the premise for the Twins reads: "Secretly, there was a third baby born, a Black baby, who hasn't been in touch with his siblings. They don't know each other and very early in the movie they meet and it's how they achieve a bond together after all these years. It's really a film about family and, no matter how different we all are, we have to learn to get along. These guys have great chemistry together, and you can see that in the reel, and how much energy they bring out in each other."

RELATED: Tracy Morgan Officially Replaces Eddie Murphy in Twins 2

Originally, the sequel was conceived with the idea of bringing in Eddie Murphy to play the twins' long-lost sibling. Murphy was even involved with putting together the script, but those plans changed when Murphy's schedule started filling up. The script for this new version of the story with Morgan was written by Dylan Dawson and Lucas Kavner.

"Twins was quite successful, and some years after, this whole thing started with Arnold meeting Eddie Murphy, and the suggestion came from one of them," Reitman told Deadline. "It was, 'I should be a triplet, that could be a very funny comedy.' We started a script with Eddie, and after the success he had with Amazon Prime on Coming 2 America, he got himself booked up heavily. And we knew we were going to make it at the beginning of next year."

Reitman added: "I'd been good friends with Tracy Morgan for a long time and always thought he was one of the funniest men in the world. I thought he would make a terrific triplet, and we rewrote the whole script for him. Now, we'll go out and try and put the money together and get it made."

"We had this fabulous deal we made with Tom Pollock, who wound up being my partner at Montecito Pictures," Reitman explains. "It was his first picture as the chairman of Universal. He loved the script and really believed in it. We decided we would do this where there was very little money upfront. We made the movie for $15 million. But it came with a lot of gross and so we ended up doing very well. In terms of future rights, Universal had very restrictive secondary rights in terms of sequels. They had to act on it very quickly, which they didn't, because we hadn't really developed it."

Of slipping back into the director's chair, Retiman also said, "I haven't directed in a couple years, but Arnold kept saying, 'c'mon, we had such a great time.' I just called him in Budapest and he's so excited to see how people respond to the reel as we send it out. The initial reaction has been very strong, and how young Arnold and Danny look and how great the chemistry is with Tracy. I had a great time doing the first one, and this is going to be fun."

Directed by Reitman, Twins was released in 1988. The comedy follows Arnold Schwarzenegger and Danny DeVito as unlikely twins separated at birth who reunite later in life. It was a big hit at the box office with more than $216 million pulled in at the box office against a budget of less than $20 million.

Triplets will reportedly start shooting in January in Boston. CAA Media Finance will handle North American sales while Rocket Science will take on international sales. They are said to be sending out a sizzle reel with the trio of actors to potential buyers. This news was first reported by Deadline.