What is the best way to perform a complex refactoring spanning multiple repositories?

Hi,

I need to re-organize a project using git. This project currently has 3 separate (central) repositories and I will need to move a large number of files back and forth between them. While doing this, there is development going on on each branch, and the restructuring will take some time. I have been continuously rebasing my refactor branches from master in each respective repository.

Is there an established way of doing this sort of complex cross repository refactoring in a way that preserves the history across repositories and takes advantage of git's rename merge logic across repositories, by say moving all repos into a third one, do the merge and move back?

Effectively, I have three repositories, A, B, and C. I want to move files from B to A and C and preserve history. This is not a simple move of one directory, but a large number of individual files being moved to new locations, renamed, updated etc. I have been working across A, B, and C, moving and updating files, but this will obviously not keep the history of the files being moved across repositories. I imagine that it would be possible to create a new repository D, import A, B, and C into sub directories, rebase to merge the individual commits on A, B, and C into one new big commit on D that will make git understand that files have been moved across, not just removed in one place and deleted from another, then apply the changes back to each individual repository?

Thanks, Kristian