Director Josh Boone revealed that the original intention was to have the worlds of Deadpool and The New Mutants crossover in a very specific manner.
The fact that Magik, one of the main leads from The New Mutants, is the younger sister of Colossus from the X-Men and Deadpool films, has piqued fan interest since the character was first revealed.
This is not the only time The New Mutants got shafted in such a manner.
The New Mutants was originally proposed as a spinoff from the live-action X-Men movies, but subsequent script changes and reshoots kept changing the DNA of the movie until it became it’s own thing, separate from the rest of the X-Men, much like the Deadpool films.