Is it possible to update only changed balances on consolidations?

We are on 11i, and have several books in currencies different than the reporting/consolidated currency, so we have to consolidate balances and not transactions.  Our process requires us to update these balances approximately 30 times in an average month (up to 3-4 times a day) during our posting/closing process. 

Currently we have to consolidate all books and then reverse all consolidations with each post, most of these journals are tens of thousands of lines, and as you can imagine, the database, and related processing times are getting out of hand.

We don't have a quick way of telling what has changed in any given book (or even if all books have changed), so our current process reverses all books and reconsolidates all books.  If, for example, book1 has no changed balances, books 2- 5, have changes but only to 10 accounts in each book have changed.  Currently  even though book1 didn't change, and for books 2-5  only 10 accounts have changed, the full consolidation is reversed and reconsolidated. We'd like to consolidate just the changes in those 40 accounts (10 accounts in 4 books), rather than the 1000's of balances for each book.