Could you clarify what you are seeing when you try to let another GitHub user see your fork of the Engine? I just ran some real quick tests with my personal GitHub account. When I was logged into my personal GitHub account (which is linked to my personal UE4 account), I could see the fork of the Engine that I have in my Epic GitHub account. I could also see my personal account’s fork when I was logged into my Epic GitHub account. Neither fork was accessible when I was logged out.
I can see what you are referring to, now. I’ll take a closer look at this next week, but just from taking a quick look at the GitHub account which has that repository, I can’t see the link to a UE4 account. I will do some checking on Monday to see what we can do to make this work for you.
I think what means is that instead of having the fork under your organization, you would make it available as a fork that is on an individual’s account (your account, for example) that is linked to a current Unreal Engine 4 account. In that case, only GitHub users who are currently members of the EpicGames GitHub organization will be able to view the fork. That would mean that they would have to have both an active Unreal Engine 4 account, as well as having it linked to their GitHub account before they could see your fork.