You may wish to migrate an existing classic branch or code line which already exists in your repository into a stream. In principle this is easy to do. The steps are:
Migrating a set of existing branches with pre-existing relationships is possible, but more complex and beyond the scope of this book. It requires careful planning and typically is the result of being conducted as a specific project. If you can, we recommend migrating project-by-project at an appropriate time in their lifecycle where you can start just by migrating a single Mainline.