Replacing an existing cost center with another

Hi All,

I was asked to change a cost center which is active and which was used for all the activities so far , to a new one. I shall expalin in detail.

One user perfored physical inventory and when she posted the difference the postings were made to a cost center which was attached to the respective G/L account. this link was made in T.Code OKB9.

Now the key user found that the cost center to which the postings were made is no longer active and they asked me to change the cost center to a new one.

Now - my doubts are:

1. I know that deleting a cost center is foolish as the docs which were posted before will not be valid in future. So how do I manage the entries which were posted earlier to this cost center?

2. I need to do this before this month end closure and they want me to transfer all the entries to the new cost center and take into account the new one only and not the old one....

how do I manage this scenario..please help me..if you think that this is a very basic question please I want you to know that I am new to FI and ofcourse I have experience in SD/MM but not FI....except the integration part....pls help me...