As general practice, no I don't get advanced authorization for $0 extensions.

For your situation, I would probably do a "If I don't hear otherwise from you by Monday at 10a, I'm filing a joint extension" to the nonresponding spouse. You can create a MFS return and only extend the responding spouse.  I'll admit I don't know how that plays out if they later file jointly and owe, if the extension covers all/half/none of the late filing penalty.  But I think that course creates reasonable cause to at least request abatement of half the late filing penalties if the IRS does apply them all.

I do get advanced authorization for auto-debits of projected balances due with extensions.  Not the formal 8879-EXT, but just written email correspondence.

For at least the responding spouse (and hopefully eventually the other one), I'd get 8821's signed so you can pulled wage & income transcripts in a month or two and know that you did get all documents. Given the turmoil in their lives, they are prone to miss stuff.

I'm sorry you're stuck in the middle on this.