When you need to add a link lead or flying lead to an existing harness it can be quite time consuming to do, you have to:
Place 2 nodes into the harness.
Attach 2 connectors to the new nodes.
Work out which wire pass through the bundle (using the Bundle Contents utility).
Relocate the wires to the new inline connector.
Add new wires from the new connector to the existing connector ensuring the wire properties macth the existing wires.
This proces is quite time consuming as you have to effectively duplicate every wire that passes through the inline, VeSys Design already has similar functionality in that an inline connector can be inserted into an existing wire.