New Problem-Merge libraries and preserve date

[Sydney's Mom]

I have my main Calibre file back, and all the dates are there. But some time ago, I created a pre-2010 and a 2010 file and removed those formats from my main Calibre library.

I did this so that my library would fit in my dropbox limit. But thanks to the generousity of Mobileread members, I now have enough space to put all my books in the same library.

So, I now have 3 libraries - main library, with all my books, but no formats for pre-2011, a 2010 library with all those books, and a pre 2010 library with those books. That means I have over 3000 entires in my main Calibre library, with no formats. Is there a way, other than one-by-one, to merge the libraries. I am fine keeping the metadata in the main Calibre library. I just want to add the 2010 and pre 2010 formats back in, without changing any metadata.

Thanks in advance, Debra