[Dovecot] Global Script to filter Spam

Dovecot Version: 1.1.1 with sieve and managesieve configured.

I want to filter spam with the subject *SPAM* to a spam folder for all users, and i also want users to have personal sieve scripts (like vacation).

I have configured Squirrelmail, dovecot manage sieve and avelsieve plugin in squirrelmail to do that.

The problem is that the user home 's scripts are replaced with the avelsieve plugin script did it in the web interface and the configuration of .dovecot.sieve calling the global script is lost.

Is there any other way to call a global script for all users not depending in the user script?

Thanks

Andrés Fernando Yacopino