Parts with physics - generating and moving together without merging


please, is in VC (4.3) some solution how generate palette with two and more part types, which will be move together without merging, just only based on gravity?
I know, i can merge them together and on target location split them, but i looking for clear solution for next work with robots.

Thank you for any advice.

Here is file, where i tried some experiments, but still without success.
Palletizing.vcmx (346.2 KB)

Source files:
Wood_board .vcmx (17.1 KB)
Palette.vcmx (65.3 KB)
Expanded_metal.vcmx (2.0 MB)