Hi Juan, you can convert lines into smooth curves in MoI by using a combination of Add pt and Delete.

Here's an example - here is a polyline that I drew with Draw curve / Lines / Polyline - I selected it and used Edit / Show pts to make its points visible:




Next I have used Edit / Add pt to insert new points nearby the original ones. New points will be a "smooth" type of point unless you check the "Make corner point" box or hold down the control key. In this case I added them as smooth points:




The last step is to delete the old corner points from the end of the old line segments - these are shown selected in the step above. After deleting those corner points you will be left with a smooth curve:




So that's how to adjust an object to convert sharp "corner" points into smooth points - you insert new smooth points and delete any old sharp points. This is a little different than bezier style, but the end result is similar.

- Michael