I would suggest any manageable curve element in a drawing be created in model sketches.
This allows full control and parametric relations. These sketches can also serve to make templates for your sketch palette.
If these curve elements are to complex to do as model sketches, you can also export them as DXF. You can open a DXF as a part file removing any of the parametric control and become simple static curve elements.
You can incorporate these models into drawings as additional models, or into assemblies. Layer management can turn on and off these models by view as needed.