To add vertex to Polyline

There are two different ways to add a vertex to existing Polyline:

With command _Pedit

• Start command and choose the line
• Choose Edit vertex from parameter
• Choose Insert to add new vertex after the visible white cross 

With editing grips

• choose the Polyline that the blue grips are visible
• Hoover the Mouse over the next grip to the planned new vertex

--> Add Vertex, Strech, Convert to Arc should be visible as commands

• Choose Add Vertex to insert new vertex