Hi Doum! Maybe my approach to the problem was the wrong: and I found this blog really interesting
Especially this post:
It does exactly what I was looking for and give us a hip file!
Really many thanks to the blogger!
And thanks to you to for your interest Doum, I hope this could help you too.
Now it's time to carefully understand the file!
Actually the blogger is Sam Hancock, so: thank you Sam!!!
My first problem was add cloth geo from the copy/pop generator. I found that my error was to leave all the particles generated from the pop network, so the solution was delete the particles with more than one frame of life. In order to do that you can give a name to the Birth Group, in the Source node, and after the pop network blast the particles outside the Birth Group.