What's the difference when giving out a landed title e.g. a county and selecting or not selecting the checkbox which is something about "all lesser titles"? (I think. Not at the game so can't recall exactly).
In handing out counties I don't think the checkbox does anything at all any more. I thought before 1.05 I had been handing out Counties and keeping the lower lords as my vassals unless I checked this, but now the Bishop and Mayor go to the new Count whether I want them to or not. I've tested my theory in the sense that checking the box on giving a county away has no real effect (it increases the verbiage), but I have not gone back to older versions to see whether my memory is correct.