How to add point exactly in the middle of the line ? I draw construcion line but the line doesn't show middle point when 'add point' command is used.

Hi Knightxor - right now I would suggest deleting the line and then drawing a new 3 point curve using Draw curve / Freeform / Control points.

Another possibility is to just add it somewhere close to the midpoint, and the select it and use the Transform / Move command to reposition it to be exactly at the midpoint.

- Michael