at-identity issue

Hi,

I use map to insert records in to 3 tables. Since we dont get any uniqe value from input I added a DocKey column in all three tables. I set the parent tables' DocKey column as Identity. Then I set the at-identity atribute in the SQL Schema. 

This map works fine when the input has one Purchase Order infomation. all the child tables getting the right values in the DocKey column.

But when the input has more than one purchase order then child tables DocKey column getting wrong values. All the new records in the child tables getting the last value of the parent Dockey values.

How can I fix this? Could any one help me to fix this please?

Siva