How to Add an Approver to an existing Approval

Hello, I have searched around and was curious if there was a way to add an Approver to an existing Approval. We want to try to have multiple Approvers attached to one type of Approval (ie like a Review Approval with multiple Approvers).

We're trying to accomplish this through extending RTC, so that we take the "Moderator" or "Detected By" and make them approvers, but if there is already an existing approval in place, we'd like to just add them to that same one...currently, it just makes a new approval for each one, and when closing the work item, it is not required that all the approvals are closed, and we'd like to make sure that everyone in the approval list 'Accepts' their approvals.

Thank you