Display upper level galleries thumbnails in a block

Hi, me again..

While I already figure out how to show parent albums, see here.

I'm trying to figure out how to show a block so that I can see upper level galleries thumbnails in a block.

eg:
Gallery X
- sub-gallery-1

- sub-gallery-2
--sub-sub-gallery-21
---- image-21
---- image-22
---- image-23
--sub-sub-gallery-22
--sub-sub-gallery-23

While seeing image-21/22/23 I want to see a block with
--sub-sub-gallery-21
--sub-sub-gallery-22
--sub-sub-gallery-23
thumbnails

I guess it is something similar to this but can't see how to change it..