You cannot directly transfer data from OU1 to OU2.
Usually, customers use interface or API to create new Transactions in OU2 for all existing open transactions in OU1.
Is that mean I create a subaccount in that book. And then create a interface to transfer it ?
It's not as simple as that. You would need to identify all the data you want to transfer across, and then use the API's to do so. It's not just a case of transferring a few tables.
Oh my God, I think I can do it easily before.