Craig, we do allow notices to be linked to each other which is a new feature we are currently rolling out. We were keen to avoid the risk of having users give new notices or instructions through a comment or a reply to a reply, so instead require a new notice, instruction, submission, etc but the new notice can be linked if required. Its explained in more detail here:- New feature - Relating associated notices across workflows
This feature is now built and going through final testing.