Hi macray - for reversing directions that's controlled by the location where you click on both curves. Click near the end of the base curve that you want to use as the start, and then click near which endpoint of the target curve you want to use as the start on that one.

But I'm not entirely sure if reversing directions is actually your problem - if you have 2 curves that are bending around in 3D space and not on a common plane then there can be banking involved when things flow along the bent curve. The best way to control that is to make the 2 curves be in one plane, there is not any way right now to explicitly control the rotation around the target curve unless the 2 curves are coplanar.

If none of this describes your issue it would help a lot if you could post the 3DM model file with your objects you are trying to flow in it. It's difficult to figure out what you are running into just from a description alone.

- Michael