OK, I was able to solve it with core Joomla way.
I had just to create a hidden, direct menu link for the multipage article and use the Joomla core "page break" button in Joomla's backend, in the JCE editor.
But this is the Joomla way, not Seblod way.
The problem was that, from the category blog view, the core Joomla pagebreak plugin wasn't able to find a direct route to the multipage article pages, that were greater than 1.
It is working now, so I am not try to find other, Seblod solution to this problem.
But, what is the Seblod solution, what is Seblod's best practice to multipage articles?
Does anybody know it?