This brings up an interesting question for writers of any kind of fiction: Should you stop your forward progress as you push through your first draft to go back and insert material into territory you've already covered--or--is stopping your forward momentum on your first pass through worth the risk of derailing your forward progress?
As we discussed this, I realized that there really isn't a definitive answer. Some writers, like the late Pulitzer Prize winner Lanford Wilson once told me, it is imperative for him to just push through that first draft and never stop and go back. Along the way, he takes quick notes of ideas he might later go back and add. But for him it was imperative to just push through to the end and then insert what else is needed throughout.
Lanford explained: "I'm writing pages, I'm not writing a play. I'm writing 90 or 102 pages, that's all I'm trying to do. I'm just trying to stack up work--in other words, to keep going...if something comes up...I'll just make a note and go on as though I've made the change. And then, as soon as I' finish, I go back and change all that."
On the other hand, sometimes in my experience there are plot elements that you suddenly discover you've skipped over or that present themselves out of the blue that need to be addressed on the spot. And the reason is that these "discoveries" have the potential to radically change the part of your story that you haven't pushed through yet.
So there's really no definitive answer to this. You just have to slog your way through that draft, whether or not you occasionally stop and go back and fix or you take Lanford's approach and finish your first draft and then go back and make adjustments. Then again, maybe it's a combination of both...?
It's a messy business.
* * * *