Can I search for parent nodes from deep child nodes using Views? I've a complicated hierarchy of nodes.
Node A contains(by node reference) multiple B nodes, each B contains multiple C nodes and so on.

Using Views will it be possible to reach C from A or vice versa given even higher depth level?

I think this is independent of D6/D7 views but I'm on D6.

There will be thousands of such nodes. Each top level A is an organization and there are a 1000 of them now. Information about each employee or department will be held in File(aka file cabinet) which again is a node).

I want to give users facility to search information from one end to another.

Update: The parent to child relationship is one to many
You can probably do it with the Corresponding Node References module. Otherwise you can't do reverse references at all. You'll use relationships, of course, to go both ways.