[uiuiii]

Hi all experts, I need the solution from the title, maybe someone has found a solution?

In fact, previously, I managed books in different libraries, i.e. Science, IT, Business, etc...

Since Calibre can neither be launched in multiple instance in order to display multiple libraries at the same time, nor having ability to display multiple libraries within 1 instance, I merge all libraries into 1, for easy searching, separated them with custom field 'Group' (like tag).

Now, the issue is, there are many books I do not always need. I keep some most useful books in laptop, but for other less important ones, I prefer to save them on external HD. With separated libraries, I can keep some libraries on external HD, rather all on my laptop. When merging so into 1 library, all files are within the same "root" folder of this library, which uses laptop HD's space, what I don't wish to.

Is there a way, to organize all books within 1 library (for searching, overview of comments, etc), but physically, the files location can be customized to be in different "root" folders (identified by class/group for instance), i.e. on external/network folders, while some of them can be locally on laptop (library's MD folder)?

Thanks for any idea...