Expanding w161 coverage

The W161 comes in a dual pack, with one unit labeled as the main router and the other as the satellite. Once both are set up, the system provides coverage up to 5500 sq ft. If this coverage is insufficient, you can connect a third-party extender to the existing W161, as it is not possible to add another W61 satellite to the system.

I have seen this answer that W161 cannot be expanded beyond one satellite. This sounds incorrect as the box clearly indicates that it is expandable to maximum of 3 surfboard max units per system. Just need to figure out how? I have seen one person being able to do it on this forum. Anyone who has done this?

Agreed. I had purchased a 2nd set attempting to join the 2nd Satellite to the existing network without success. There might be a certain firmware required as the process went through never joined the existing network