Formula to split last name before comman and all names after comma into separate cells

You can use Data | Text to columns to do this.

Alternatively, you can put this formula in B1:

=LEFT(A1,FIND(",",A1)-1)

and this in C1:

=TRIM(RIGHT(A1,LEN(A1)-FIND(",",A1)))

and then copy these down as far as you need to.

Hope this helps.

Pete