Retained Earning cumulative balance at year end

Hey Experts,

Our accounting structure is Company , Department(BSV), Natural account, Cost Center, Product

I have a query how to GL creates a Retained Earning Account Combination for each BSV and how this will transfer the balance at the year end.

I have read that Secondary tracking segment cannot be assigned to BSV segment so in our case what would be secondary tracking segment so we get a retained earning reports at the year end on each BSV.