Import existing Album Sets into new LR Catalog

Hi there,
I’ve got several Album Sets on my web space. When I create a new Catalog in LR I only see the default album but no existing album or set. I have no problem connecting to the root gallery folder and also creating new albums or sets work fine. But I need to publish a new album inside an existing album set from within Lightroom. Creating the same album set inside LR to create that path is not possible. Publisher then creates a new folder on the web.
can you please help me out?

Lightroom Publisher albums and album sets are catalog specific. You cannot just add to existing sets or albums from a different catalog. This is a Lightroom limitation.
You have a couple of options to try.

If you absolutely need to control the album sets from Lightroom, you can try installing the Lightroom Voyager plug-in to transfer Publisher collections from one catalog to another. This would also transfer the images from one catalog to the next, I believe.
https://alloyphoto.com/plugins/lrvoyager/

The other option is to use Backlight Publisher to publish from the second catalog. This takes Lightroom out of the Publishing process. You would need to first export images at the needed size and then create new albums in your album sets and upload, all using Backlight Publisher.

I tried it with the LR Voyager Plugin … and it workes fine. I only import the structure without the images into a new catalog. Then I can use the existing album sets and publish new albums there within Lightroom. Thank you for this information.