codeigniter logic of PC/tl/sc/pm email

i have an array like this 
Array
(
   [0] => Array
       (
        [PM] => 14
        [LD] => 578
        [TL] => 56
        [SC] => 67
        [PC] => 
       )

) The above are just id of PC/PM/TL/LD , i will then query them to a table to get thier email ids And i want to use the logic where my email template should work like PC in “To” and rest all CC’ed If no PC assigned, then TL in to email rest all in cc If no TL, then LD in to email rest all in cc If no LD, then PM in to email rest all in cc If no PM, then SC in to email rest all in cc