How to add new collection?

[fotografie]

Hello,

running out of space on my harddrive which holds my collection, I have
to store the picture on an other drive.

Now my question:

How to add the collection to my existing collection? What would happen
if I import the new ones? Would they be copied into the old ones? (It
would not be the thing I want to do!)

My wish would be to have the following tree:

Album

- HD 1

--- directory 1 to 356

- HD 2

--- directory 1 - X

Thanks in advance for your heldp.

Sorry for the question, but I did not find anythig in the menue that
would help.

Kind regards

Ulf