Your question spans a couple of relevant issues. For naming purposes, let's call your first two RDSR objects A1 and B1.
First, you should not send the revised objects using the SOP Instance UIDs of A1 and B1.
A premise of DICOM is that two instances with the same SOP Instance UID have the same content.
(Yes there are exception cases but those have to be described and handled very carefully)
So the receiving system may see the "new" incoming object as a resend of the original A1 and choose to discard the new one as a duplicate.
Also, if the original A1 has been retrieved by anyone there are now two (or many) copies of the SOP Instance and if they have different contents, then the situation rapidly gets confusing.
So the new objects should have new SOP Instance UIDs of A2 and B2.
A2 will have the same Study UID as A1 since they still belong to the same study, and B2 will have the same Study UID as B1.
A2 would likely use the same Series UID as A1 since your pattern is likely to put all RDSRs together in a series, but you could put it in a new series.
In this scenario, A2 and B2 should contain all the irradiation events for exam A and exam B respectively.
That means A2 contains one less irradiation event, and B2 contains one more irradiation event.
In a simpler scenario where exam C and exam D were completed correctly and C1 and D1 were sent, then there was a request for an additional exposure in exam D, you could send RDSR D2 with only the single new irradiation event or you could include all the exam D events.
Since RDSRs include an Irradiation Event UID (0008,3010) for each irradiation event, later analysis can load all the RDSRs and recognize any duplicate events from their UIDs.
The final question is what to do with the "bad" RDSRs (A1 and A2).
Most PACS have manual tools and exception queues for cleaning up bad data, so you could arrange to have A1 and B1 deleted.
Some PACS are starting to support the IHE IOCM Profile (Imaging Object Change Management) which allows "bad" objects to be flagged and automatically sequestered and/or deleted by the PACS, and allows for such flags to be passed along to federated PACS systems.
Hope that's helpful.