For traveling up the chain your method is the best. For getting replies to a tweet there is an undocumented API [1] that was implemented with #newtwitter that returns some responses.

You could also use the third-party API that Twitoaster provides. Twitoaster will generally only work if the user who created tweet that started the conversation is a Twitoaster user.

[1] http://app.apigee.com/console/apigee-console-snapshots-12833... [2] http://twitoaster.com/api/