I noticed that the block library (the list below "Global blocks" when editing) will show the same blocks for all sites with the same language.
Is there a way to show the block library per site instead of per language?
It seems to be very common that the globalBlockFolderId and siteBlockFolderId settings found in EPiServer.config are set to be the same.
Have you tried having different values on siteBlockFolderId for each site?
Just what I needed, thank you :-)