[Vtigercrm-developers] Questions on Importing Invoice, Quotes, Salesorder

[mat]

Greetings vtdevs,

I've installed vt6 along side of my old 5.2.1, in a export/reimport
strategy 
onto version 6, to workaround numerous migration issues. 

Now, I have an issue on vt6 concerning importing properly invoices (same
for quotes and Salesorder module). 

Briefly speaking :
While on Contacts & Leads modules import process shows Step 3 to
configure
the duplicate records handling, for Invoice, SalesOrder, Quotes modules
this
Step 3 frame  does not show up (ie I checked that the frame doesn't not
exist in the page). 
This lead to inconsistent imports for these  modules : I need to
configure the criteria fields for duplicate merging to prevent automerge
(ie if subject is matching then it automatically merges the records) and
define an advanced merge
process based on fields criteria.

I spend some hours checking on various browser, looking in the
user/developer's forums, in the code yet had no chance in the easy way.
A bit perplex, I expected a ("manual") duplicate records handling
like... or rather even as much as for Leads because frankly speaking
invoices with same subject are more common than lead with same FirstName
LastName ; aren't them ?

Just to confirm/go further : 
- is it  actually supported to handle duplicate records for those
modules ?
- if not, is it a planned feature or even already assigned ?
- can I help in implementing it (somebody interested on the list) ?

Thanks,
Mathdesc