> Problem is when updating the site. If one child file as 
been
> added and the parent one modified from the main site i get
> this result:
> ..
> that means each file stored on disk before, is 
automaticaly
> renamed and consequently winhttrack has to regrab the all
> site instead of just updating the parent one and adding 
the
> last child.

No, no. Update and local naming is totally independent: the 
cache is able to deliver up-to-date data even if httrack 
has to rename the files on the local filesystem (the cache 
is address+URI based, and httrack dynamically matched 
address+URI, and local filename). If pages are re-
downloaded instead of being updated, this is a SERVER 
issue: the server is not able to "understand" update 
requests (Etag and/or Date)

If you want to keep similar names even when updating, use 
something like:
%n%q.%t
(%q is a hash value based on query string)

(the -2, -3.. are generated on-the-fly by the naming system 
when a collision is detected ; that is, when the default 
address+URI transformation to a local filename gives an 
existing name with a different address+URI)

> that is to say, there is no need to redownload old files 
and
> process is very quick now??
Again, httrack should only issue an update request, and the 
server should only respond by sending an "up-to-date" 
message reply.

(You can check that using Set Options / Experts Only / 
Activate debug mode, and check the hts-ioinfo.txt file 
which tracks all HTTP client requests and server responses)