Problem Using Binding Source with Relations..

Hi All,
I am creating a C# winform in Dot Net ,
I have a datagridview control & a few Other Controls (2 Textbox).
In my DataSet there are two tables MasterParent(Code) ,MasterDetail(ParentCode).
Both are related by a FkRelation. Code is an AutoIncrementing Column.
I Create a binding source (b1) & set Mastertable as a DataSource to it. Now I assign b1 as a datsource to GridView.
I create another Binding Source(b2) & set b1 as datasource and fkRelation as DataMember.
Now I bind, the 2 textbox controls to b2 (by using DataBindings of TextBox).
In both the binding sources, AllowNew,AllowEdit,AllowRemove is set to true.
What I want to achieve is :
Whenever User Enters a new Record in datagridview, a New Row should get added in the Relation, For this I use UserAddedNew Row event of gridview & Call b2.AddNew();Also I set the FK Relation ParentCode in the textbox.
However, Once I Commit the gridview Row (i.e By moving up & down ), the Form View (i.e the texbox controls) Lose their Add new Event, and no data for b2 gets committed to the data source.
Kindly Help..