Hi Marouane
As I specified you can add the products in the dynamic navigation scenario in my code above,where I have specified a comment :
"" AFTER RECEIVING THIS LR_ENTITY , you can create it's bol relation to initiate any fields on web ui."
Use the normal BOL programming to add products like :
1. Fetch BTAdminH from BTOrder through relations of BTOrder.
2. Create related entity BTAdminI of BTAdminH . ( Creates an Item on opportunity ).
3. Add the product id on the created item from step 2 ( BTAdminI->set_property( ........... ) )
/Hasan