Overlap Beams in Time?

[PMA]

Dear List:

First, thank you for Lilypond -- this wonderful tool -- and for 
accepting my subscription.

I am placing noteheads, and using beams, in a way that has little to do 
with common usage.
Lilypond has to a considerable extent "played along", as you'll see in 
the attached example.

But you see also what I *can't* make Lilypond do: overlap beams symbols 
in *time*.  I want
a separate beam above the staff, connecting those A's.

Metrically of course that's preposterous, so if I code the 2nd set of 
"[...]"s, Lilypond screams
	Preprocessing graphical objects...ERROR: Wrong type (expecting real 
number): \
            #<unknown-type (0x27 . 0x9381190) @ 0xb6cca970>

Does anybody know a way around this predicament?  I've scoured the docs 
and wiki in vain.

All ideas will be appreciated.
Thanks in advance,
Peter A.

P.S.  My last resort would be to add the second beam later -- by force 
-- within a PDF editor.
       But accuracy in that context is tough, and I haven't yet seen 
such an editor with Undo.

lapped-beams.pdf
Description: Adobe PDF document