Rescue 3
The "slot computer" (CASA) does live in Brussels but the flight data that's fed into it comes both from IFPU1 in Brussels and IFPU2 in Bretigny. Re-routing wise, ETFMS (FMD has changed it's name) have more limited capabilities than IFPS. The reroutings are done in the IFPU's using the normal tools; the Ifps system and brain power.
Frosty Hoar
Point taken on the fuel example. I still remember the hectic days when I worked in Ops myself until I got wise and ran away to Euroland.
Reoutings can normally be found without a major change of flown milage. Of course, if your destination is for example Manchester and the regulation is in the close vicinity of Manchester Airport, theres no way you are going to get out of it.
Cheers