Hi Javier,
I'm not sure for how many users (why not all?) you need to set this up, but you can use wildcards (*) in the user name fields (see below).
Also, by default I think there are just 2 slots available for creating filters. You can use more if you adjust the rsau/selection_slots parameter.
Also, the rsau/user_selection parameter seems to be of advantage for you:
Defines the user selection method used inside kernel functions. Set this parameter to enable the use of ABAP patterns asterisk (*) for any character string, plus sign for any single character, and number sign (#) to escape wildcards, spaces at the ends of strings, and such. Otherwise only asterisk (*) is a wildcard.
Note
To create an audit log for the user SAP*, you must enable generic user selection and escape the asterisk. Enter SAP#*.
see here for more info