Opening balances for prior periods need to be transferred from Primary ledger to Secondary Ledger.
Opening balances need to be initialized in GL for the newly added ALC / secondary ledger based on the prior balances of the primary ledger.
These would form the part of a data initialization process.
I have a business case where, the PrImary ledgers are have data from Sep-2013 onwards.
We are planning to Introduce Secondary Ledgers in the Middle of Next year -- 2014. (May 2014 eg. )
Now the data from the Primary Ledger in the periods (Sep 2013, till May 2014) needs to be transferred to Secondary ledger as part of Data initialization of the opening balances.
Also, When Go Live in May 2014. we will be again loading balances in the primary ledger from the Dec 2012 periods onwards. This data , will automatically flow in to defined existing secondary ledgers as per the conversion.