Originally Posted by JP
No. They were doing First Class AND Magneto, until Singer came on board and decided to make the films focus be Xavier and Magneto.
This entire film is is Singer's brain child.
I disagree. They probably felt Singer would only be involved in one film for now, and they trusted him to combine the projects. They had a script for both and then they decided to merge to story lines for whatever reason. I doubt Singer was just doing his own thing and ignored those scripts. There was probably collaboration to unify it into one story. It's not like Singers team wrote the original screen play to this. They probably took input from both scripts.