Fake sender exclusion in siv

Hello all, I am working on quarantining all messages claming from originating from our domain.  Using the following .siv code.  

# attr NAME=Check for fake senders
    if anyof(address :all :matches :comparator "i;ascii-casemap" ["from"]
                                                                 ["**xyz.com"],
    envelope :comparator "i;ascii-casemap" :all :matches ["from"]
                                                         ["**xyz.com"])
    {
        pmx_quarantine "Fake Sender";
        stop;
    }

This was from a earlier thread I started:

/search?q= 1519

However, I ran into the following snag regarding an exclusion we need to make.  We need to allow certain legitimate emails that come from our domain through.  So I created a list and made the followig changes to the rule:

   # attr NAME=Quarantine fake senders from our domain
    if anyof(address :all :matches :comparator "i;ascii-casemap" ["from"]
                     ["**xyz.com"],
             envelope :comparator "i;ascii-casemap" :all :matches ["from"]
                      ["**xyz.com"])
    {
        # attr NAME=Allow these senders to pass
        if anyof(envelope :comparator "i;ascii-casemap" :all :memberof ["from"]
                          ["fake-sender-opt-outs"],
                 address :all :memberof :comparator "i;ascii-casemap" ["from"]
                         ["fake-sender-opt-outs"])
        {
            keep;
            pmx_mark1 "external_inbound_fake_sender_allow";
        }
        # attr NAME=Quarantine the rest
        if envelope :comparator "i;ascii-casemap" :all :contains ["from"]
                    ["**xyz.com"]
                address :all :contains :comparator "i;ascii-casemap" ["from"]
                     ["**xyz.com"])
        {
            pmx_quarantine "fake_sender";
            pmx_mark1 "external_inbound_fake_sender";
        }
    }

I am thinking however there is an excessive number of checks with my logic here since, I am testing twice for the xyz.com domain.  Can someone advise on how he/she would approach what I am trying to accomplish?

Thanks