Embedding Audio Tracks Within Each Other With Audacity

A friend came to me with a request to create an Audacity plugin that, given two stereo audio tracks, takes the second audio track and ensures that it stays X decibels below the first audio track. The project did not take long after establishing just what it means for a track to be quieter than another, despite me having never written anything in a LISP dialect (Audacity uses Nyquist/XLISP) and some of the oddities of Audacity that I will describe below.