 <p>Add your forked Sylius repository like this in your composer.json</p> <pre><code>"repositories": [ { "type": "git", "url": "https://github.com/ylastapis/Sylius.git" }], </code></pre> <p>You can either require your master branch or create a custom branch (to merge your code pending that Sylius team accepts your merge, mine is called master-poc)</p> <p>In the require section, require YOUR branch, prefixed by "dev-". so master became dev-master, thus my branch master-poc is now dev-master-poc </p> <pre><code>"require": { "sylius/sylius": "dev-master-poc" }, </code></pre> <p>I also got a branch alias, Can't remember if it's still usefull</p> <pre><code> "extra": { "branch-alias": { "dev-master": "1.0-dev" } } </code></pre> <p>Some link to the doc: <a href="https://getcomposer.org/doc/05-repositories.md#loading-a-package-from-a-vcs-repository" rel="nofollow">https://getcomposer.org/doc/05-repositories.md#loading-a-package-from-a-vcs-repository</a></p>