The rules for preserving document versions are based on their being associated with the document’s inode number, and on the same volume. Here are the details and a way to preserve them whatever.
Versatility
It has been built into macOS and many apps over the last 14 years, but must be one of its least used features. How versions can empower your editing of documents.
Convert a document into a folder containing all its saved versions, and unarchive that folder back into a document with all those saved versions. All using drag-and-drop.
The Eclectic Light Company 