Rest API Method for branching with multiple source repositories

The new branch functionality shows great promise. But, and there's always a but, it doesn't handle plans with multiple source repositories.

For an example setup, I have code stored in the following svn locations:

/svn/libraries/core/trunk
/svn/libraries/widget-creator/trunk
/svn/applications/magic-8-ball/trunk

To create a clean build of the magic-8-ball application, I need to check out all three in order and build them. If I want to branch the magic-8-ball application for release and have it depend on specific versions of its libraries, the source directories might be:

/svn/libraries/core/branches/3.14
/svn/libraries/widget-creator/branches/12345
/svn/applications/magic-8-ball/branches/1.2

From a functional perspective, each of the source repositories in a plan needs to be able to have a separate source repository path when building a given branch. This path for the default build, this other path when building the '1.2' branch etc.

On the UI side when configuring a Bamboo Branch, the current location for specifying a different source repository when building for a branch is partially non-intuitive. To my mind, especially if Bamboo's concept of Branch builds becomes more central to Bamboo's operation, having the different source repositories for Branches as additional options in the Configuration -> Source Repositories -> Edit Source Repository tab would make more sense. For Branch (pulldown) use [this] repository information with [x] same password or different password etc. I really like the idea of not having to retype the same repository password multiple times.