[O] Agenda filtering

[Richard Lawrence]

Hi everyone,

I have an Org file with a lot of projects that look like this:

* TODO Project A
  DEADLINE: <2016-10-28 Fri>
** NEXT Subtask 1
** TODO Subtask 2

* TODO Project B
  DEADLINE: <2016-10-31 Mon>
** DONE Subtask 1
** NEXT Subtask 2

Some of these projects have deadlines far in the future, some near.  I'd
like to focus on just the NEXT tasks for projects with upcoming
deadlines.

Is there a simple way for me to say to the agenda, "Show me all (and
only) the NEXT tasks that are part of a project whose deadline is before
(say) 2016-11-01"?  It seems like this should be possible with the
built-in agenda but I can't quite figure it out.  The tricky thing is
filtering by the deadline of the parent project, which might be several
levels up.

Many thanks for your insights!

Best,
Richard