It is possible that there is a function in the curves that allows you to create a composite curve, another solution: extrude 2 surfaces / make the intersection curve of the 2 surfaces.
I would add the following clarification to Mr. Souchet's very pertinent answer. When projecting one sketch onto another, it is necessary to clearly visualize the relative positions of the two sketches. Since this amounts to the intersection of two extruded surfaces, the nature of their overlap is important. If there is one that sticks out, it's not a big deal, but you have to know it. See attached drawing. But in Ollinger's case, this is not the case.
Thank you very much for your answers, I'll try these functions and see how it goes! Pierre Mihailovic's drawing corresponds exactly to the type of curve I am trying to make