Bi-Directional Relationship With A SubForm

Bi-Directional Relationship With A SubForm

Dear all,

            I'm struggling with 3 questions for more than 14hrs and still i didn't get solved. So any one can help me on this??

1) How to fetch records from parent form and update records in subform using Script.

 Example : Form - Orders
 SubForm - Products

 When i select a specific order all the products related to that order has to display in subform and when i save, that has to save to "products form" as well as in "products subform". Even if i add products related to that orders in "products Form" that has to show in subform when i go to "orders Form".

 I guess this can be done with Bi-Directional Relationship.
 
 Now my second question is

2) How To Create A Bi-Directional Relationship With A SubForm.

           When i went through this Sample app. Everything was good but the thing is i can't understand how he add that subform as a Bi-Directional field.

            Now my third question is

3) Can we pass one subform data to another subform? (Like we pass one form data to another form)