Just make the node visible. All its ancestors will automatically be
expanded. After all, how can you see a child node without seeing the
parent chain?
Hmmm, I just noticed this was cross-posted to the ASP.NET group. It's
helpful if you mention that you're doing this on a Web form if you're going
to cross-post to a general group like C#, because some folks (like me!) will
assume you're talking about a native Windows tree view control, and not a
Web control. Now I'm not positive that my answer will help you, because I'm
not a Web programmer and I don't know if that tree view behaves the same
way, although I'd think it would in this case.