How does Cosimo's mother and father try to get him to come down from the trees and what does Biagio do?

The Generalessa has gotten over her initial panic, and she and the Baron decide to take a nonchalant stroll through the garden so they might ignore Cosimo and thereby antagonize him out of the trees. The most helpful affect of their stroll is that it allows Biagio to lay out the geography of the trees into which Cosimo has climbed.