Great idea @RafalZ!
It got me thinking though. I’m not saying this is the best way to do what @solidsilver wants to do–often when you’re talking about wanting exacting control over the placement of instances you’re getting into nanomesh territory rather than a curve function. Remember that you can always use a curve stroke to draw out simple control geometry, like a tube, then manipulate the topology to exactly size or place the nanos.
However, following up on RafalZ’s idea there are some other options for doing this that don’t require you to break the curve. It just comes down to using a combination of selection modes with Frame Mesh. It would not have occurred to me before RafalZ’s post.
In the following example, you’ll see that I have used polygroups to define where I want to place the curve, and used Zmodeler to crease a single edge connected to that border. When I then Frame Mesh with both Polygroups and Creased Edges enabled, it places the point at that intersection.
If this kind of polygroup/topology manipulation is too destructive to your mesh, create a duplicate subtool to create the curve with.