On Mon, Apr 3, 2017 at 6:34 AM, Bob Newell <bobnewell@bobnewell.net> wrote:

Or even simpler: you want to group together a bunch of scattered
headlines that you now see as being related. Yes, you can do this by
moving each one around individually, but I'd like a faster method---
just mark them and relocate them all at once to the top or bottom of the
buffer.

If you need it fast and simple, and you're in an agenda view, you can use M-up, M-down to reorder the headlines you see, and this doesn't modify anything else, just the visual order in this agenda. Then when all the tasks you want are at the top, you can copy/paste them, or mark them and move them, etc.