Hi,
In your use case, the functional exchange cannot be created from the project explorer view neither from the fast linker.
If you don’t want to scroll or unzoom, you can for instance create a new LDFB diagram, drag-n-drop your two logical functions, create the functional exchange using the palette tool, save, delete the diagram, go back to your previous diagram and as it is synchronized, the new link will be displayed.
That’s the only way I see to cover your need.
Regards,
Christophe