How do I combine repositories without losing history?

[CG]

I want to merge two repositories (or more) into a single repository without losing history of either repository, but have the full history of both available in the new repo.

I have project1 and project2, each in their own repo (repo1 and repo2). Each project’s folder structure is set up the same—i.e. there’s a “/src” folder, a “/build” folder, etc in each. I want to bring each project (along with history) into a new repo where the /main will eventually (after some tweaking) have a folder structure such as:

  /project1/src
  /project1/build
  /project2/src
  /project2/build

So, in Plastic I imagine doing this as follows: I’d like to have a new repo with a /main branch. And then create two child branches off that (called say “/main/repo1” and “/main/repo2”). And then on each of those child branches import the “/main” branch of each of the two repositories. This would let me have the full history of both on their own branches and then I could merge those two branches together after making changes to the folder structure in each so I could merge as above.

However I can’t figure out how to do this in plastic. Attempting to “pull remote branch” or replicate a repo doesn’t work as desired in this case (I can’t sync a src repo to a specific branch in a target repo, at least not I am aware of).

So first question, is there a way to synchronize an entire source repository to a specific child branch in a destination repository that I want to map as the main for the source repo? If so, how do I do that?

Second question, if there’s no way to do that, then is there any other way to do what I want?

I’m sure others have wanted to combine or split repositories over the years, how have you preserved history in that case?