Question about Repeating Material in Papers

Hi,

I am in the process of publishing my first academic papers and am in a bit of a tricky situation, would appreciate your input. I’m in the humanities:

I have two papers, paper A and paper B, submitted to two different journals. Both have come back with revise and resubmit requests. Paper A requires a medium/major revision and paper B requires a minor revision.

Paper B “repeats” some of the material of Paper A. Not directly, of course. Paper B is a comparative study of three figures. And Paper A is a major historical expansion on one of the three figures. However, this figure has not been written much about before, and so some of my own original research repeats in both papers.

At this point, I have submitted the revision for paper A, and I am currently revising Paper B. However, I expect Paper B to be published first. What, if anything, do I need to tell the editor of Paper A? I don’t have a source to cite at the moment, since Paper B has not been published yet. Is there such a thing as citing an upcoming (unpublished) paper? I want to be as transparent as possible, but also without making things unnecessary complicated (I know that it is already complicated).

I want to emphasize that nothing is copy-paste, and that the material has a legitimate reason for repetition. The portion of the “repeated” material in paper B is around 2700 words in length, while paper A, which expands upon this material and places it in a wider context, is 12,000 words. While sharing some of the same larger themes, the purpose of each paper is fundamentally different. One is very historical, and one is far more conceptual/speculative.

Thanks in advance for any thoughts to a new author!