How to modify a final draft to reflect that a conjecture in its preprint was refuted? I am currently in the process of trying to publish a mathematics paper. A draft of this paper had been posted on arxiv, which contained an interesting conjecture.

In the intervening time, this conjecture has been refuted by another group of authors. I am not sure how I should edit my paper to reflect this.

One option that is out of the question is to simply delete the conjecture from the paper. The problem with this is that the latter paper has cited this conjecture as its motivation. If I removed the conjecture, I would be pulling the legs out from the subsequent paper.

What I am leaning toward is to state something along the lines of "In an earlier draft, we had made the following conjecture:" and then include some discussion and citations about how the conjecture has subsequently been refuted.  

Note that most of my paper is unaffected by this refutation, and in fact I still believe that the conjecture could hold for the special case I need

Is there a better way of handling this situation?
If you can prove or at least make a convincing case for the conjecture in the special case you need, I'd do the following:


Describe the conjecture in the special case
Prove or make the convincing case in the special case
Write "in a previous draft, we expected this conjecture to hold generally. However, it has subsequently been shown ..."


If you can't or don't want to argue for the conjecture in your special case, then your formulation works as well.