You should create a separate search index and configure SearchBox control to use it. When you open SerchBox control for editing there is a drop down from where you can choose an index catalog.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items