Squid Peer Configuration Possible?

[abalsam]

I am looking at setting up a pair of SQUID proxies to cache linux updates in an HAproxy configuration.  Since ideally I want to minimize the number of times a package is downloaded, I want to configure the proxies to either sync caches (not seeing how to do that within Squid) or configure each instance to query the other instance as a peer.  The plugin looks like it only has an option for a parent.

Any help/guidance would be appreciated.

Thanks