Hi @jMac35
As far as I’m aware Google Docs doesn’t offer a way to add a signature in a document, so if you’re looking for something official you’ll need to use a different app. There are lots of apps for signing official documents like Adobe Sign, Pandadoc, HelloSign and many others (those are just the ones I can think of off the top of my head, and are not an endorsement).
With the Zapier Google Drive integration you can change the sharing preference of a Google Doc, so you can add permissions for parties to be able to comment on the document, but there isn’t then a way to trigger a Zap (a workflow) based on those changes.
All in all, I know you don’t want to use other apps, but it sounds like you’re looking for an app that is set up to manage documents for signature, you probably want to take it out of Google Docs entirely. There’s a good chance that there’s one that works in the way that you’ve described.