Salary Differentials for location and grade combination

Summary:

Looking for some guidance on possibilities, please.

Two years ago, we created a salary differential based on work location and a factor (e.g., 0.85, 1, or 1.1). This means we have one grade rate which uses the min, mid, and max values of 1X factor, and the salary differential is attached at the 'Salary' salary basis.

Now I am being asked if for certain grades we can just use a factor of 1 irrespective of location?

What are the recommended/cleanest approaches to do this (that is not a large yearly maintenance lift)? I am hoping to avoid creating a new salary basis as that would mean we would have many many reports, alerts, interfaces, etc. that would break.