Some source control programs allow you to "merge" those changes into the two branches, but everyone I've ever talked to...and they've used many different source control tools...has said it was far easier to manually make the changes than to try to do the automated merge.

>No. Generally, the point of branching is to maintain two (or more) copies of some piece of code. For example, you release version 1 of your app. Then you start working on version 2. While you're working on it a bug is discovered in version 1 that you need to fix. You don't want to fix it in the current code tree, since you've got a bunch of changes for release 2 in it. In that case, you would branch release 1. In that branch, you make your bug fixes. I think most devs. just manually make their bug fix changes in both branches.