The situation you have is you want to conduct a special event that has players from other clubs attending and you want to have the ratings processed as normal. The players attending are not on your normal members file and particularly their rating information is not on file.
First consider how rating information is on your masterfile. The only players that are rated are those at your club and play regularly there. In other words they are members of your club. If the players are likely to play at two clubs regularly they should be permanently on the file. The ratings of a player are only on file after the cards file is applied at start of the month.
Now for the special event situation. Any such event can be run using a special masterfile for the event. Request from the CARDS administrator a cards file with the clubs involved included. In this case ask for a "special" ratings file with participating club members from the list of clubs included. In the club details of the new masterfile (specialevent.gdb) put 'myspecial' or something meaningful in the "ratings club name". Do not add any players to the file as that will be done from the cards file sent to you. Then when you get the myspecial.cds file use the [imports][player ratings] option, update using the myspecial.cds file, applying as start of month (or read start of event). All the players at the participating clubs will be added to the file but the details of the players will not include addresses etc., but they are not needed for this purpose.
Run the event using this special masterfile, finalise the event as usual. Then [export] the event as the "myspecial.rat" file. You typically do not use that masterfile for any other occasions, but there may be several "events" (qualifying/finals/plate...etc) in the export.
After the next month end update the players' statements online at http://www.bridgecentral.com will include this event.