[O] complex searches with org-sparse-tree

[Sebastian Fischmeister]

Hello,

Is there a possibility to get a sparse tree for a more complex query?
For review purposes, I would like to get a sparse tree with

(SCHEDULED <= <today>) [if scheduled is set]
or
SCHEDULED is not set

(org-sparse-tree) seems to be able to only to give me the first part,
but it neither can give me a sparse tree where the SCHEDULED is not
set nor can I merge the query.

Any ideas?

Thanks,
  Sebastian