Here is the progress so far:
I managed to make new face-to-face activity in Moodle and to add upload function for administrator purposes under mod/newf2f/mod_form.php
The upload function is based on the Import Grades functionality, sofar I did't changed anything in it, as it accepts Excel and cvs fiels.
The question here is, how to manage the communication between the Import of the file and the data for the face-to-face, this way the data for the face-to-face will be filled from the excel file at the time of the import, not manually from the administrator.
It should be like reverse function of "Export attendance" in the sessions page of F2F, where we get all the data for the sessions (start data, finish date, room, status, first name, surname, etc.)
It sounds very complicated, or it is just to me this way, as I am new in developing custom functionality to Moodle.
Any help/advice will be appreciated.