Currently for RSVP registrations if we merge a new LO record with a existing RE record, the registration will become frozen in the RELO plug-in. To prevent this from happening, we have to creat a new record, process (import) the RSVP registration, then go back and merge the records. This is a very cumbersome process and if we do not catch them, will cause multiple duplicate records in The Raiser's Edge.
For some reason this does not occur with records that have gift transactions. For those can be merged in the plug-in and the transactions are successfully transfereed to the existing records.
This should be resolved with the most recent product release. You can reject the registration in the plug in, resend it back from LO to RE and it will get associated with the right constituent.