One workaround would be to have two exact copies of the pdf, one in a Session and another outside a Session. You could then copy and shift+ctrl+v the selected comments to the Session version, this will hold references to the page. All selected comments copies would default to the person copying them into the Session, but this might accomplish what you are trying to do.
Not exactly import, but a spin off of it. You could filter all the comments as needed on the source or some variant of that to accomplish what you want or have more control.
