In May of 2018 I asked for a utility to combine *.pwa files and was told it might be coming in the next update. Still nothing as far as I can tell, and I have the latest version.
So I started reading additional forum posts and found talk about "drag and drop". I can open multiple PWA files, which appear as tabs. I hoped that I could just drag entries from on tab into another, but that doesn't work. So what is it used for?
Drag and drop is used to move items or folders within one file.
For transferring data between multiple files open these files and use copy and paste. You can copy and paste entire folder(s) including any sub-folders or just selected items. Copy from one file, then switch to another file tab and paste where required. If you use Cut operation in source then items will be moved, with Copy operation copied.
Copy and paste of items and folders is completely secure, no plain text is copied to clipboard.