Editable curve within component

Two days ago, I managed this without a hitch, making six apertures in a gear wheel by manipulating a single Bezier within a component:
It was a breeze, but I must’ve forgotten a step in the improvised workflow, given that I can’t replicate the process now.
I can’t make a component from just the curve I want to manipulate, and I can’t edit that curve once it’s grouped and/or componented within a plane or volume.
What am I missing here?