[leafnode-list] Retrieve older articles

[Enrico C]

Is there a way to have leafnode retrieve nnn (say 100) older articles on
server?
Let's say the upstrea server has articles 1 to 10,000 for an interesting
group,
I would like to only retrieve articles 1 to 1,000 the first time I run
fetchnews,
then 1,001 to 2,000 the second time, and so on.
I couldn't such an  option in the /etc/news/leafnode/config file. It seems
to me you can only set how many articles you want to retrieve counting from
the last, not from the first on server.