Can hags still cast when members of their coven die?

My last D&D session included a fight against a coven of sea hags. Hags have some interesting and a bit ambiguous rules about how the coven works. One of the rules was this:

Shared Spellcasting (Coven Only)

While all three members of a hag coven are within 30 feet of one another, they can each cast the following spells from the wizard’s spell list but must share the spell slots among themselves[…]

The question is do the hags have to be alive for this to still work. The party focused attacks on a single hag to reduce the threat, but would killing one member of a coven have stopped the spellcasting? Would killing two have stopped the last member from being considered a coven and being able to cast?

Does a Sea Hag’s Death Glare work on a creature that is averting its eyes?

The Sea Hag has a special action called Death Glare:

Death Glare. The hag targets one frightened creature she can see within 30 ft. of her. If the target can see the hag, it must succeed on a DC 11 Wisdom saving throw against this magic or drop to 0 hit points.

Does this work on a target that is averting its eyes?

Does the Detect good and evil spell see through a Night Hag’s etheralness? [5e]

The system is 5e.

I’m in a weird spot with my campaign, where my party is taking on a night hag. They are lvl 5 adventurers. They have no access to see invisibility currently since the only spellcaster is a cleric and a healing focused warlock. We left off last week with the hag disappearing and they cast detect good and evil. I elected to end the session there because the session was already 3 hours in (which is about how long our sessions go) and also because I wasn’t sure how to rule this. I would think that detect good and evil works for this, at least that’s the way I’m leaning but some clarification on the same would be much appreciated.

Can three summoned hags form a coven?

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.

Can one Hag be apart of multiple Covens, and gain the benefits? Can one Coven of Hags form multiple covens using the same set of Hags?

I’ve been messing around with Hag Covens and not that I don’t think they are weak or anything (because they are anything but), I just wanted to add some extra flare to a particular Hag I’ve got in my world.

I’m curious if it’s possible for one Hag to be apart of multiple Covens and the rules for that, or for three Hags to form more than one Coven using the same three hags, in order to gain more coven spells and such?