It is possible, with DM Approval, for high level player character to summon a trio of hags (either a trio of Sea Hags from a single Level 8 Casting of Conjure Woodland Beings, or a trio of higher CR hags by three separate castings of Conjure Fey). Both of those spells have a duration of an hour (or two, if the Extended Metamagic spell option is somehow applied onto them), after which point the hags disappear.
With DM Approval, can such a trio of temporarily summoned hags form a coven (do they potentially have the time to do so) and/or can it be said, again with DM Approval, that they were already in a coven when summoned ?
This is within the scope of Adventurers League Organized Play, where Rules as Written are to be followed, with a modicum of Rules as Cool. I ask, because there might be something I'm missing.