>> Likely `org-element-map' allows to extract headings. There are should 
>> be some example in the mail list archive and at worg (hacks, perhaps 
>> in FAQ).
> 
> See also info "(org) Using the Mapping API"
> https://orgmode.org/manual/Using-the-Mapping-API.html
> for `org-map-entries'.

Thanks for the suggestion, but these look like really low level 
functions which involve a lot of coding. Will try if I can figure out 
something.

Best,
Reza