Extend and merge free-form paths
Use the Pen tool to continue drawing an existing open path
and to merge paths.
Resume drawing an existing open path
In the Tools panel, select the Pen tool.
Click the end point and continue the path.
Merge two open paths
When
you connect two paths, the topmost path's stroke, fill, and filter
attributes become the attributes of the newly merged path.
Select the Pen tool in the Tools panel.
Click the end point of one of the paths.
Move the pointer to the end point of the other path and click.
Auto-join similar open paths
You
can join one open path with another that has similar stroke and
fill characteristics.
Select an open path.
Choose the Subselection tool and drag an end point of the
path within a few pixels of the end point of the similar path.