Updating a Multi Entity view object to add row only to child entity

Question

I have a View object VO1 made of multiple entities e.g. EO1 and EO2 which have a composition association with cardinality 1 is to many EO1 being the entity corresponding to parent table and EO2 is the child table. All the entities in the association are updatable.
The data is displayed using VO1 on the page. So for each row in child table, parent table attributes are dispalyed correctly due to the join condition.
If I create a new record on the VO1 iterator using the create operation binding and save it, it correctly saves a new record in header table and related child table.
Now I need to provide with one more create operation on the page such that when user can add a child row for the existing header row using the same screen.
Essentially I need a create operation which, on selecting a row from the displayed table which is based on VO1 , creates a new row in the VO1 iterator such that the EO1 attributes are pre filled with the header table information from the selected row and the child attributes can be added by the user and submitted.
Tried Using create with params on VO1 by passing the header information, this lets me enter the data on screen just the way its required ,but this obviously only tries to add a new record to header table with the existing primary key itself and the operation fails on save giving duplicate key error for the header table.
Unable to figure out where to change the default behavior to fetch a exisitng entity rather than create a new entity in the header table entity object for this multiple entity VO1.

Answer 1

Hi ,
So how do i send in the sample. Do i send in the code base don HR schema ..
Or just explain the above with emp dept tables.