Hoping that my question is appropriate for MO, I would like to ask the following question: I have sent one of the editors of a very good math journal a paper of mine which contains a main result, call it theorem A. The editor wrote me that he sent my paper to referee and will contact me when he will get the referee's report (this was 7 weeks ago). A week ago I have noticed that my Theorem A can be generalized to Theorem B, and Theorem B has a nice application, which Theorem A does not have.
What should I do:
(1) Should I be patient and wait for the referee's report, and only after receiving it decide what to do with my Theorem B?
(2) Should I inform the editor about my Theorem B and let him decide whether to send it to the referee or not? On the one hand, I do not want to disturb the editor (and referee), but on the other hand, perhaps the referee will be glad to see my Theorem B? (if he is not sure if my Theorem A is good enough to be published in their very good math journal, but Theorem B is).
This question is slightly similar, but it asks about fixing an error, not about generalizing a result.
Thank you very much!
Edit: I have just found this question, which is quite similar to mine, though there are differences between the two.