Migrating Multiple ClearCase Branches to RTC

Our team has a vob that builds multiple products (ex: Product_A, Product_B, Product_C).  The main branch build Product_A.  There are also other product specific branches that have some files that are different.  The majority of the file are shared with multiple products and are not branched. (see a v-tree depiction below for product specific files Diagram may not show properly).  We are using Base Clearcase and use labels when releasing the product versions.  All product source code reside on either the main branch or the product specific branch.  This product line has been around for years of development.  We just want to migrate the release labels.

I think we understand how to migrate Product_A.  We use the Baseline Importer (labels locked, attribute created and ordered based on label version) to import the main branch to the main stream in RTC.  I assume when the migration takes place, are the labels also migrated? 

What we are unclear about is how to migrate the product specific branches.  We want to keep the shared code and only migrate the product specific files to another stream in RTC (I think).  How do we accomplish that using the Baseline Importer?  Do we create another product stream in RTC at the baseline where he ClearCase branch was based from and migrate the labels for Product_B and target it to the new product stream.  Will that import all code to that stream (we do not want) or only the versions with release labels on the product specific branch?  And there are  versions on the main branch with the Product_B labels.  How do we migrate that to the main branch (they may be different from the versions labels with Product_A - see example v-tree below: Diagram may not show properly).

Is there a better way to accomplish this?

Most of the examples on jazz.net describe only migrating a single branch/single product build.  Are there reference material that describe scenarios like this one?