Classic GL to New GL

One of my clients implemented new GL long back in 2011. They did this mid year rather than in an new year.

The GL balance was not uploaded to new GL. They had the "Read from GLT0" indicator activated so in effect even though new GL was implemented they were not using it.

Now I want to deactivate "Read from GLT0" table indicator. But the issue is FAGLFLEXT balance is not tying back to GLT0 balance (as new GL was implemented mid year and the balance was not copied to new GL).

Is there a way to bring the new GL tables in synch with GLT0 table?

Sandeep.