Alternative raised hand reaction

Frequently in fairly large meetings, we'll want to have a structured discussion. A number of people raise their hands, and we want to go through them in order and address the questions or topics that each wants to discuss. Others might want to contribute to an ongoing discussion (rather than start a new one), and so raise their hands. But there's no nice way I've found to distinguish "My hand is up to start a new discussion" from "My hand is up to contribute to the ongoing discussion."

Is there a nice way anyone has found to do this?