Numbers is unable to sort on the Last Name.
You must separate the first name from the last one.
Often it's easy to do that automatically but sometimes it's not.
Here is my workaround
in column B the formula is:
=IF(ISERROR(SEARCH(" ",$A)),"",MID($A,1,SEARCH(" ",$A)-1))
in column C the formula is:
=IF(ISERROR(SEARCH(" ",$A)),$A,TRIM(RIGHT($A,LEN($A)-SEARCH(" ",$A))))
in column D the formula is:
=IF(ISERROR(SEARCH(" ",$C)),"","CAUTION")
Sort upon column D to locate easily cases with multiple first (or last) names to treat them by hand.
Then sort upon column C.
When I treat a case with mutiple spaces, I replace some of them by NOBREAK SPACE (alt + space) as I did here for the defunct Ford Snooks EAGLIN.
Yvan KOENIG (from FRANCE lundi 2 mars 2009 22:12:39)