Hi,
for example I have a train full of seats and I would like to apply material variations A/B/C. I can do it by edit block, but how to switch between different assignments per Snapshot? Couldn’t the material assignment of embed blocks no be saved to snapshot states? Maybe it’s a bug that it doesn’t work yet and can be fixed in the next time. 
It would be very helpful for my next project.
-Micha
If you want to be able to change materials on a block you should set the objects to By Parent before blocking them. Materials set to By Parent will use the material that is set to the block instance.
My seat blocks contain approx. five materials, some needs to be changed for the different design versions. The “by parent” works for a single material per block only or?
Unfortunately yes. Not sure if you could fiddle with the material settings through a script, that is assuming you can access the materials from blocks just through the (render)material table.
Do you know who develops Snapshot and can be asked for Snapshot support of embedded blocks?
@lars wrote Snapshots, but I’m guessing the answer is going to be no for changes to blocks.