[squid-users] Routing Via different Parents

Hi,

I am having some trouble configuring squid to achieve the following.
A certain domain xyz.example.com can be accessed via ProxyXYZ. All
other sites (INCLUDING xyz.example.com) can be accessed via ProxyABC.
The Link to ProxyXYZ is provided under a special contract and is
of limited bandwidth, but is a good way to save money but routing
requests for any sites in the xyz.example.com domain via the Proxy
server on that network. I would really appreciate any config tips
to allow the following

1). Access to the Internet should go via Parent ProxyABC or
if that is unavaiable then go Direct.

2). Access to *.xyz.example.com should (DEFAULT) go via ProxyXYZ or
if unavalaible via ProxyABC or else go Direct (As for 1)

I have the following in my config, but I have only ever
setup vanilla Squid Caches.

-----------------------
cache_peer proxyXYZ.example.com parent 8080 0 no-query no-digest
cache_peer proxyABC.upstreamISP.com parent 3128 0 no-query default
no-digest

acl XYZ dstdomain .xyz.example.com
acl ALL src 0.0.0.0/0.0.0.0

cache_peer_domain proxyXYZ.example.com .xyz.example.com
cache_peer_access proxyXYZ.example.com allow XYZ
cache_peer_access proxyXYZ.example.com deny ALL
cache_peer_access proxyABC.upstreamISP.com allow ALL
-----------------------

I'm just not sure that this is the best way of doing it.
I have had a look at prefer_direct and hierarchical_direct but
I'm not sure which is the best way to go. Any help or pointers
appreciated.

--
Scott Muller