Android Studio now has learned to work with githubGitHub fork repositories (you don't even have to add "upstream" remote repository by console command).
Open menu VCS -> gitVCS → Git
andAnd pay attention to 2the two last popup menu items:
Rebase my github forkRebase my GitHub fork
Create pull requestCreate Pull Request
Try them. I use the first one to synchronize my local repository. Anyway the branches from the parent remoteremote repository ("upstream") will be accessible in Android Studio after you click "Rebase my githubGitHub fork", and you will be able to operate with them easily.
(I use Android Studio 3.0 with "git"Git integration" and "github""GitHub" plugins.)
[![enter image description here][1]][1]
[1]: https://i.sstatic.net/2poHE.png