Can I transfer master pages from one document to another?

I am designing a very long book, 550 odd pages and 208,000 words. I have just two master pages so far: A which carries the book title and pages number and B which is blank. Almost all the pages use the A master.

The book has 37 chapters, each with a title, and it occurred to me that it might look better to have each relevant chapter title at the top of each page instead of just the book titel. I always work on a ‘test’ document and have one such in which I have created and additional 37 masters, each different for each chapter.

I am about a third of a way through when I realised I might be wasting my time: I am not working on the main document but on a test document and will have to start from scratch, creating all those masters for the main document.

So I thought I might stop and ask for advice: is there ANY way I can transfer the masters from one document to the other?

I had thought of copying and pasting the main document copy into the test document (the one with the chapter headings) but as the main document is divided into self-contained stories (to enable me to add endnotes with the endnotes of different chapters starting afresh at i, ii, iii, iv etc) I would have to copy and paste the text of each story individually.

That’s fine and I don’t mind doing the work, but in my experience it also leads to all kind of glitches.

So: is there ANY of transferring the 37 master pages I am creating in my test document to the main document, or must I start anew?