Steven, thanks for that.
This will make it easier/better going forward.
However, the problem I have at present is that where previously the "album Artist" option grouped songs under the artist shown, for some unknown reason they are now shown separately. It will take a long long time to go through the thousands of songs in my library and correct using "multiple splitter tag". Could this have something to do with a "bug" in a particular version of M?
As a M user from the very early days I have never encountered this problem before.