This folder is exclusive for only OC related stories and can not include the Mane Six at all in any sort of way.

No references, no mention of anything related to the characters.

But you can include the town Ponyville in a Alternate universe type field. You can include ponies around Ponyville or any locations around Equestria that don't involve the Mane Six in anyway - that's if you put up Alternate universe tag in your story.

Then, again? You can have Celestia and among other characters that are related to the show but can have no involvement or knowledge of the mane six. Basically? Just make it Alternate universe again and well all be fine.