I hope I'm not making another mistake, but I think that this post
https://www.caminodesantiago.me/community/threads/caminho-nascente-fatima-tomar.38892/ has additional information about how pilgrims can walk from the Caminho de Santiago to Fatima and then back to the Caminho again. The recommendation seems to be, go to Tomar (no one walking from Lisbon should miss the opportunity to visit Tomar, IMO) and from there take the Caminho Nascente.
To round out the discussion, Rodrigo, a question about leaving Fatima. Am I right that the pilgrim has to choose between going back to Tomar to rejoin the Caminho de Santiago, or continuing on the Caminho Norte de Fatima, which will reconnect with the Caminho de Santiago near Coimbra?
Of course for those who don't mind hopping on a bus, I assume there is transportation available from either Tomar or Santarem for a day visit?
I have seen an increase in interest from Santiago pilgrims who want to include Fatima in their caminho, so I really appreciate your organization's interest in reaching out to that group. Laurie