Exchange rate customizing - SKK/EUR

As Slovakia will be joining the Euro area on 01.01.2009, I did the

currency customizing as explained in OSS Note 1231768.

In this note is mentioned to one time add the official fixed exchange rate using transaction OB08, with

validity date 01.01.1800

My problem is that our datawarehouse department needs to use the exchange rate added in OB08 with

the most recent validity date. In terms of date, the most recent rate will be the one from December and the rate will not be correct for their tools (as the correct one will have validity date 01.01.1800).

My question is can I add another line in OB08 with the official rate and validity date

01.01.2009? What are the potential impacts?

Many thanks for your help,

Regards,

Ben