problem using function module for infotype 21

hi

im uploading the infotype 21 (family details) through function module hr_infotype_operations. i found that infotype 0106 (family/related person)

is a secondary infotype and that a record is created for 0106 ,everytime you create a record in 21. so i upload the family data of an employee using the function module for infotype 21 initially. and then fetch the same record from the table pa0106 and modify the same record with other information.

for example : u have the address details of a dependent(father subtype 11) in infotype 21. this address data is stored in the table pa0106 . im not able to modify the record for infotype 0106 using the function module 0106.

i would like to know the reason for the same. Is it because that infotype 0106 is a secondary infotype and u cannot modify the record using the fn module..?/

thanks

sridharan