Part of "G. Schirmer Opera Anthology" series.
The book is not explicit about when arranging of music, or recordings, took place. Where relationships are attributed to "1991–2011" or "–1991", it is a guess based on the following facts. The book claims copyright dates of 1991, 2008, and 2011. That seems to say that part of the total work was completed in each of those years. Nothing says explicitly when any task began. The Editor's Foreward, talking about the arrangements, is dated March 1991. Thus it seems likely that the arrangements were complete by then. The Diction Coach CD's (1 & 2) have copyright dates of 2008 on the media. The Accompaniment CD's (1 & 2) have copyright dates of 2011 on the media.
MB Works for this Release
In the future, it might be an improvement to create Works specifically for the Larsen arrangement of each accompaniment track, and link the Recordings to that instead. These Larsen Works will connect to the catch-all Work with an Arrangement-Of Relationship. Similarly, it might be good to create Works for each diction coach track, with a Relationship (but which?) to the same catch-all Works.
There are pros and cons to creating these Larsen-specific Works. See Style/Classical/Works, forum thread Book of carefully-edited songs, with CD: what Works?, and forum thread 'Thoughts on data model: MB-Works, music scores, and FRBR-Expressions. One objection to Release-specific Works is that it's hard to tell whether a particular Recording is performed from that Work, but with the Larsen anthology, we know for certain that they performed this arrangement — it's the point of the anthology.
Release 26 Italian Songs and Arias by Paton is similar to this one: a carefully-edited collection of song and aria scores, supplied as both printed scores and Recordings of non-vocal performances of those scores.