Avast Enterprise Administration - Select Active Directory OU for Discovery Task?

Hello,
I was wondering if I can drill down to a specific OU for the Discovery Task on Avast Ent Console, as there are quote a few pcs that I do not require Avast to be installed on, however the scan detects all computers on the domain, and our licenses are not being allocated correctly.
I have setup a schedule so the Discovery Task is ran each night, so if i delete the 50odd computers that I do not need, they reappear the next morning.
Any help would be appreciated.
My only though is to kill the scheduled scan, remove irrelevant computers, then manually add computers that I know of as they come on to our network?
Seems a bit backwards.
Cheers