Alter filegroups in partition scheme

Let's say that you have partitioning, where the partition scheme looks like this:

CREATE PARTITION SCHEME myRangePS2
AS PARTITION myRangePF2
TO ( test1fg, test1fg, test1fg, test1fg );

Now you want to go to this:

CREATE PARTITION SCHEME myRangePS2
AS PARTITION myRangePF2
TO ( test1fg, test2fg, test3fg, test4fg );

I was thinking that would be a simple ALTER PARTITION SCHEME, but that doesn't seem to be possible. What is the easiest way to do this?

Ola Hallengren
http://ola.hallengren.com