The other leg continues to move. This causes the fly to turn until both feet are in the sugar water. The contact with sugar water is also leads to neurotransmitters to be released that cause motor cells that control proboscis extension and feeding behavior. When the fly has ingested a certain amount of food, neurotransmitters are released that inhibit all of the above behaviors. That is, touching sugar elicits firing of sensory neurons, but their firing and the release of neurotransmitters does not affect the inhibition of leg movement or proboscis extension or feeding behavior.
Divergence refers to the fact that one stimulus can affect many responses.
A pinprick to a foot of a cat causes the leg to lift up. But, just as automatically, the three other legs adjust so that the cat doesn't fall over. The stimulus causes a pattern of responses. Divergence means one cause, many effects. Convergence refers to many different stimuli can cause the exact same response.