@stwert Thanks for keeping me stepping deeper into the "Attach Brush to Curves" thing :-D

I´ve done the following:
Created 3 curves (in my example 3 circles) and did Paint FX > Curve Utilities > Attach Brush to Curves on them. Maya is generating for each curve a new Stroke + Brush Node.

For better controlling I simply disconnected brush2 and brush3 from their StrokeShape and instead connected brush1. So I´m able to setup one brush and getting the result on all 3 curves (which are now strokes).

Since now you can delete your curves, brush2 and brush3 and the result will be 3 strokes attached to one brush.

Time to start a project and test it in practice.