Display the posts on a special Blog in the network NOT in the activity stream

I have manage a site with buddypress and blog network, within this I also want to build up a support blog. But I do not want that the new posts (and commets) from this blog will be displayed in the activity stream on the mainsite. On the other hand all postings from the blogs of my members should be displayed as now in the activity stream.

Has someone an idea, knows a plugin or something like this as a problem solution ?