Academic integrity question on self-referencing and changing a paper after acceptance The day before yesterday I got an acceptance letter for a conference paper, with the ability to make some minor revisions over the next week.

This will be my first conference for my PhD so it's a fairly important milestone.

The thing is, I submitted some work in progress to a small workshop half a year ago, got accepted, and presented that WIP there. There were no proceedings, so apart from the presentation (powerpoint slides) that I gave, no materials were ever publicly released to this day.

The conference paper was written very last minute and hastily, based on some results, and I asked my supervisor what I had to do with the workshop abstract. Typically for him, he replied "whatever". So I didn't do anything with the abstract while writing on the conference paper, and just left it to gather dust on my laptop.

Right now, I feel like I could use the extra "publicity" that 2 extra entries on my scholar profile would give me, but I'm not sure what to do with the workshop abstract. It's not exactly building on the same method, but does use the same data, and has an interesting conclusion, that wouldn't hurt to mention in the conference paper. However, that would change the narrative a bit (the improvements over previous state of the art would be less significant, even though that's not entirely the point).

I probably made a mistake by not archiving and referencing this work in progress in the conference paper in the first place (do you think so?)? That being said, what's done is done, and I want to proceed in the most ethical way possible.

If I archive the workshop abstract, I feel like I ethically have to cite the abstract in my conference paper, because otherwise I pretend that the improvement is bigger than it is. But then, I would suddenly add new references to the paper citing my own work, that was never seen by the reviewers. And that feels very unethical to me.

If I don't archive the workshop abstract, I might still use the results in later follow up work. I think this is the proper solution, since it was never published.

What should I do? Should I ignore the existence of the workshop abstract and take the hit in visibility in the scientific community? Or should I cite it in the conference paper? Is the latter ethical?
I would talk to my supervisor, but he is totally not approachable about these things. He usually says "don't bother me with this trivial stuff" rather than helping, if it's not a question directly related to my research. So I have no clue what is right to do.
By my understanding:* You've presented some work-in-progress at a workshop, without proceedings. You have a conference paper accepted and you've been invited to make some minor revisions. The workshop presentation is built upon data used by the conference paper, but the methodologies are different. The workshop presentation drew a conclusion that you're contemplating including in the conference paper, albeit, that would change the narrative a bit. You feel that you made a mistake by not [citing the workshop presentation] in the conference paper. You're also concerned that not citing the workshop presentation would mean that you pretend that the improvement is bigger than it is, albeit, you're concerned that adding a new citation, which reviewers haven't seen, is very unethical. You're considering building upon your workshop presentation in the future and publishing that work later (and you consider this as the proper solution).

My thoughts: 


You are under no obligation to cite your works-in-progress, especially those that are unpublished. That said, you may choose to. 
You should not extend your conference paper to include new ideas - e.g., the conclusion you drew in your workshop presentation - since they haven't been peer-reviewed. 
You could later publish your work-in-progress with citations to your prior conference paper. Alternatively, you could combine that work-in-progress with your conference paper to derive a journal article, the former aspect would be considered a new contribution (since it hasn't been published previously). In both cases, you could - if you wanted - cite your workshop presentation, since it presented some early results.




*I've summarised my understanding, since I'm not sure I've correctly understood the details presented by the OP.