I think you do have to deregister for that race. Anyone who makes at least 3 of the 6 races and has asked to be included in the Series can qualify. This year the scoring is being done by teams though so if you have someone who is sailing for your team they can still be scored under your team ranking and your team wouldn't have to dereigster. Brian will have a seperate registration for each event on the 1design.net forum. At the very least I would at least ask over there.