Moving seated orders to a new facility map

Hi

We are re-developing our website and there is a change to SYOS. With new display we need to change the facility map to display the seats better for  the customer. However, this affects productions that are currently onsale some of whcih have performance that are already selling right the way through 2012.

The physical seats aren't changing so will only require mapping seat_ids, performance_nos and zone_nos to new performances using the new facility map and was thinking of updating the following tables t_lineitem, t_sub_lineitem, t_transaction, t_order_seat_history and tx_perf_seat (with the EIS tables at later stage).

This has to be automated as much as possible as will probably need to do this a few hours before the new site launch, and while the existing site is switched off,

Is there a better or simpler way of doing this?

Thanks

Mark