Let me start simple: I enjoy Space Ponyos concept and universe. I haven't read all the fics(don't want to read clop), but here's the thing that bothers me. Headers.
I'm a Foe fan, and, as a reader, I could easily look for relevant fics just by putting "Fallout Equestria" into search. It... doesn't really work that way in this particular subfandom for reasons I cannot fathom.

Dear authors, if it isn't that much of a problem, do the header thing labeling your fiction as one belonging to Space Ponyos universe, please?

6523269
Or just browse through the group. That's what it's there for.

6523285
I agree with you, albeit partially, for there could be some fic or another that isn't in that group, but still on fimfic.

6523296
Then it should be added to the group.

6523362
And how could I find it in the first place without stumbling by accident?

6523363
Well, I mean, you're posting a thread in this group asking authors to do a thing to make it easier to find their stories meant for this continuity.

If you don't think adding their story to the group will help any, neither will your solution. They'd have to be in this group to see your thread. You are only reaching people who are in this group with your idea. It isn't magically spreading out through the internets to enlighten random folks that they ought to mark their story for you.

Really think that over for a moment. 100% of the people who you fear won't be able to add their story to this group? Will also not see your message suggesting they mark your story so you can find it. How do you propose to find these people and get the to go along with your suggestion, and if you do reach those people why wouldn't you simply add their stories to the group, or get them to join the group so they can add it themselves?

By all means, do think up some scenario where, for some reason, adding the story to this group doesn't help any, but your own suggestion somehow does. If you can come up with those scenarios, by all means, mention them. That would actually be a merit of your idea over simply adding them to the group.

6523442
I agree, there is a certain paradox here which I didn't think through.
I would propose authors of submitted stories to add Space Ponyos to their header, thus creating a trend of sorts, or a standard, if you will.
Hm... you know those moments when previously good idea seems like a convoluted illogical mess? That's the one. Thank you for time spent and forgive me for not thinking whole situation through.

6523474
No prob.

I'd imagine your FO:E fics, despite using this "header" also are all in a group. Making that header pretty useless. If people want to find FO:E fics, they can just look through the group's folders. On the plus side, if the folders are particularly useful, that can help them find things like "canon" stories accepted by Kkat as part of the proper continuity vs "AU" fics, sort of like how Space Ponyo's folders are set up.

6523498
Thank you again.

Not all of them, actually, just because there are a ton of them and I kinda grew accustomed to such a tradition, feels weird otherwise. If it isn't a header then mentioned "set in such and such universe".
The only canon, despite obvious implications, is FoE. Everything else, even fics that got their approval, well... just in this case with Shino, "as canon as you wish them to be".