Ahhh, just realized we are talking at cross purposes (and you certainly clarified it a number of times in your posts!).
I am surprised you can even apply the Author (year) option at all to a multiple citation. – that is usually reserved for a single citation because the situation you are trying to use, won’t work at all for usual multiple citations which have different authors.
My solution would be to go back to the old fashion way of handling these, and hide the authors in both (Author, Year) format of these and type the author name in.
Sorry.