nested directors

[KiT Sin]

is it possible to define a director using a set of directors?

i'm hoping to use hash director in varnish with a configuration like
below, so that whenever a backend squid is down, cache miss can be
avoided when varnish redistributes traffic away from the failed server.

e.g.

director rr1 round-robin {
    {
	.backend = squid1;
    }
    {
	.backend = squid2;
    }
}
	
director rr2 round-robin {
    {
	.backend = squid3;
    }
    {
	.backend = squid4;
    }
}
	
director rr3 round-robin {
    {
	.backend = squid5;
    }
    {
	.backend = squid6;
    }
}
	
director layer7 hash {
    {
	.backend = rr1;
    }
    {
	.backend = rr2;
    }
    {
	.backend = rr3;
    }
}

thanks
kit