PROPAGATION trough Nepenthes flowers : HOW?

Hello to everyone!
This time it is me that needs help!
It is easy to receive seed from the union of 2 Nepenthes?
If I have a male and a female nepenthes how is the procedure to have seeds from them?
It is easy? It is enough to give pollen just to a single male stigma?
Last question : Ibrid seeds are not sterile,or?
I hope that I can use the seeds!
thanks for any help!

Mr_Aga
Milan - ITALY