From the main FAQ[1]: How do I submit Unreal Engine 4 changes back to Epic? GitHub is our channel through which the community can fork and modify Epic's code

From the main FAQ[1]: How do I submit Unreal Engine 4 changes back to Epic? GitHub is our channel through which the community can fork and modify Epic's code alongside our own engineering team. Source code changes you check in at GitHub will be viewed by the community, and if the vetting process goes well, we'll incorporate your code into UE4. This means you'll help lots of people! 1: https://www.unrealengine.com/faq https://www.unrealengine.com/faq