Mass Reversal....and posting through LSMW

Dear Gurus,

We hv data from last months. In some of the documents didnt updated/ missing the Business Area. Wht is the best way to solve this?

-- Can we Directly update necessary tables ( BA based on Plant wise i.e both are same name). If Yes wht are the tables need to update.

-- If we do mass reversal of all document and re-post through LSMW. If yes,

What will to do for clrng documents. Can we need to do.

Can anybody did like this, can u share ur exp or problems.

Regards,

Venkat