In one embodiment, a method comprises determining, by a controller device in a low power and lossy network (LLN), that a first LLN border device is in a first personal area network (PAN) having a first directed acyclic graph (DAG) topology, and that the first LLN border device is a neighbor of a second LLN border device in a second PAN of the LLN having a second DAG topology; receiving a path request for a third LLN device in the first PAN to reach a fourth LLN device in the second PAN; and generating an inter-PAN path between the third LLN device and the fourth LLN device via the first and second LLN border devices, the inter-PAN path providing a stitching between the first DAG topology and the second DAG topology.