Not sure whether you should combine majors the way you are talking about doing it, since the PGA season that included the most recent PGA tournament is actually completed. There was no US Open in that particular season.
The new season started, and the plan is for 6 majors this season, including two Masters tournaments and two US Opens.
Obviously, y'all can set it up however you want to, and I guess you could do last season's PGA, this season's first US Open, and this season's first Masters as "the majors" for your contest (without last season's Open Championship, which wasn't played); or, you could run it the way the PGA runs it, and have a super-mega 6 majors contest.
Since I didn't set it up and I don't run it, I'll leave it up to whomever is "in charge." Just wanted to point out what the PGA is doing.
"We are not provided with wisdom, we must discover it for ourselves, after a journey through the wilderness which no one else can take for us, an effort which no one can spare us, for our wisdom is the point of view from which we come at last to regard the world." --M. Proust