Cannot forward update of anti-virus to office sites

[semperfi]

I have my anti-virus on my my head office getting the update on internet dowloaded to my AV server and muticast to officec workstations.
Then I have my two office site located on different places then connected by a lease line VPN. My problem is my AV Server on the sites cannot get update to the head office AV Server even i pushed the AV update from Head Office to my two office sites. The AV uses TCP port 8192-8194 for multicast update.

You can my network diagram for reference.