No need for refork. You can create release branch by yourself and checkout Epic’s upstream/release to that branch.
Here’s how it’s done: http://stackoverflow.com/questions/4410091-import-upstream-branch-into-fork
Of course first you should make sure that you have upstream remote added:
[FONT=Courier New]D:\UE4\UnrealEngine [release]> git remote -v
origin https://.com/FamilioDevel/UnrealEngine.git (fetch)
origin https://.com/FamilioDevel/UnrealEngine.git (push)
upstream https://.com/EpicGames/UnrealEngine.git (fetch)
upstream https://.com/EpicGames/UnrealEngine.git (push)
If you don’t you should add it by command:
[FONT=Courier New]git remote add upstream https://.com/EpicGames/UnrealEngine.git