What we do in our plugin is to deactivate our metadata in each field that is created by PB in order to not to have duplicity of information. And because we believe the educational metadata is the key of the system and should be created inside of the PB Core. (our plugin works also without PB). Our developer is almost finishing the plugin and the time with us and we would like to know wich properties he have to deactivate in our plugin because are in yours. That´s why we would like to know wich LRMI properties are you using or if you are extending with other properties.
You can take a look in a few days, we almost finish the educational part of our plugin. https://github.com/books4languages/pressbooks-metadata
We believe a web book can´t be a web book if is not possible to tag with metadata everything. We can say we have metadata for 2 puporses. Metadata for general information and for educational information.
General information means: All the schema types and properties that you can find at schema.org.
Educational means: LRMI and some other creative work properties for the relations and some controled vocabulary for the fields (we will not use in the future once pb metadata is finish).
Also we can create metadata as Super admin and to share the information in all the book info sections or all the chapters. or as Admin in all the chapters.
The point is: we believe there are other properties that are necesary as extension of the LRMI. Maybe coursePrerequisites (in oder to know what is necesary before to start to read the book), isPartOf or other few properties for a full understanding of the relations between books. Also we are creating a field for categories and subcategories in order to make possible to create relations with the chapters and between books. But we are thinking which could be the best properties for that, we have some ideas but is complicate.
In order to make possible to have a web book, we believe the relations with the content are important too.
Also we are creating dropdown menu with the key vocabulary for some fields. We do all as neutral as possible in order to make all of you possible to use. But we have a complement that extend for language content creators.
We believe that maybe webpage is not the best one of the schema Types for Chapter. As if we have a book for cover page, maybe for a chapter the Article type is more related.
Anyway, in our plugin we allow for the educational metadata section to choose between a short collection of Types: Course, Book, Article, Webpage… in order to le the users to choose the best one for each situation.