In the GECKs you could use Ctrl+G to group objects together, and the group then would be saved as a new NIF file. This could be used to make building easier by not having to select each single object everytime you want to move a group (like a shelf or a laid table for example), but it also had the advantage that the textures were joined when possible, and a whole floor of matching room-tiles would load only one set of textures ingame. Of course the SCOL Nifs could also be used as a quick way to make statics out of havoked objects.
The CK still has the "Static Collection" goup, but it's empty and Ctrl+G no longer works. Am I blind and there is a new variant or was the grouping-function removed for good?