As you can see in the picture I'm how to copy the square along the curve in Catia V5?
The only way i know how to do this is to use an "axis to axis" translation for every instance you require and project those into a single sketch
Answered with a tutorial: https://grabcad.com/tutorials/how-to-copy-translate-a-pattern-along-a-curve-in-catia
Maybe this helps: Create equidistant points along the curve first:
then use them to place the squares.
If the yellow curves in your sketch are two curves, select both of them first and right click->selected objects -> concatenate. This will generate a new, combined curve.