The expansion of Angular Whimsies is complete . . . and indeed the piece works so nicely as a quartet, that I am revisiting the original duet, just to make sure I find nothing "deficient" in the piece in that form.
The quartet thus done, I have sent whither it needs to be sent.
And word is just in from Nana Tchikhinashvili in The Netherlands; she very kindly plans to bring my Magnificat back into her choir's repertory not only for concerts in May and June, but for an event in Rome in October.