If I have opened Nautilus and spawned a new Nautilus instance, a new PID is created for the new Nautilus instance. Shortly after, the instance is joined with the main Nautilus program running.
Main nautilus instance:
manos@box:~$ ps aux | grep nautilus manos 2687 1.1 2.0 1190968 77580 ? Sl 11:40 0:24 /usr/bin/nautilus --gapplication-service
Spawning a new instance:
manos@box:~$ nautilus&  15447
Shortly, PID 15447 disappears as it joins 2687. Is there a way to follow this? Namely is there a general way to see that 15447 "becomes" 2687?