Auto link:

When you pass on a succession of sketch entities with common ends, this function allows you to automatically chain the entities together into a passing contour.

You can either:

Select the sketch entity to reach,

Select on  OK , it will continue as far as possible on connected entities.

When you have a junction with several possible pathes, TopSolid will choose one unspecified. If you want to impose one of them, select the previous sketch entity to the junction, the one you want after the junction and select the  AUTO LINK  button again if needed.

The auto link stops if:

The path is closed (it will finish on the starting element to get a closed contour),

The last sketch entity of the contour is reached,

The selected target sketch entity is reached.

As long as the path is not closed it is possible to continue.