Mark SVN external references changes in the build log name

Hi all,
I have an svn repository called eg. "MAIN" with external reference to another repository called "REF. Build configuration has only one VCS root so when a new code is commited to any of those repos build is run in TC.

I need to mark up/separate changes to the external REF from MAIN in emails with build log.

Example: new commit to MAIN (#1245), then commit to REF (#366),  another commit to REF (#367) and commit to MAIN (#1246). In the email will be shown:

Change 1245  by Bryan
description of change #1245 to MAIN
Change 1245  by Adam
description of change #366 to REF
Change 1245  by Adam
description of change #367 to REF
Change 1246  by Bryan
description of change #1246 to MAIN

What I need is something like

Change 1245  (REF #366) by Adam
description of change #366 to REF

Is it possible to do that somehow? Shall I create new VCS root only for external repository?

Thanks for any help and ideas.

I use TeamCity Professional  6.0.3 (build 15925).