If you are working in an organisation where GitHub is used as a source code hosting site, then this post will be a helpful one for you.

Nowadays, as devs, we are following some of the best practices like forking the repository from the main organisation's account, and we come across a situation wherein you want to collaborate with your peer on a feature and you decide to push the code on the same branch.

Some of the commands that would work on the peer's forked repository (Can be followed in this order) :-

git remote add theirUsername https://github.com/theirUsername/repoName

git fetch theirUsername

git checkout -b myLocalBranch theirUsername/theirBranch

git add/commit the changes

git push https://github.com/theirUsername/repoName HEAD:branchName

git pull https://github.com/theirUsername/repoName branchName

Hope this post will help you in better collaboration in a long run.
Happy learning !!