Merging IDEA Code Coverage - Parallel Dependencies

I  have a project with multiple configurations under it. At each step it runs unit tests with coverage enabled and I would like to merge those results for the top-level configuration so it shows the overall coverage.

Now, I think I can copy up the .teamcity/coverage_idea/ to subsequent steps using dependencies. The problem is I have one point where the tree branches and two configurations can run in parallel. For example:

    A
    |
    B
    |
   ---
  |   |
  C   D
  |   |
   ---
    |
    E

The problem is with the "E" step because simply using the dependency copy aproach will cause D to overwrite C's data, so one of the two will be lost.

Is there a command or something to merge two sets of coverage data?

I am using IDEA's coverage for Ant with TeamCity 7.0.1.