This should help :

Have a derived col. Have three cols in there as (assume F1 is your excel col):

First_name

expression :SUBSTRING((REPLACE(F1,","," ")),1,FINDSTRING(F1," ",1))

Last_name

expression :

SUBSTRING(F1,FINDSTRING(F1," ",1) + 1,FINDSTRING(F1 + " "," ",2) - FINDSTRING(F1," ",1) - 1)

middle_name

expression :

(FINDSTRING(F1," ",2) > 0) ? REPLACE(SUBSTRING(F1,FINDSTRING(F1," ",2) + 1,FINDSTRING(F1 + " "," ",3) - FINDSTRING(F1," ",2) - 1),".","") : " "

Please let me know if this worked or not