How to link source files between releases

I didn't find any info related to this in the help. In our previous SCM tool, we could link files between releases of our product, so that when checking in fixes in the current release they would be automatically applied to previous release streams. What is the recommended procedure for accomplishing this with Jazz Team Concert? Also, what is the recommended procedure for checking in identical changes to files across releases where links have already been broken? Are there any plans to improve this process in the future?

Thanks for your help!