Re: 1240 as non-rootbridge associated to 1240 as non-rootbridge
The answer to your question is YES. You can extend you your network by connecting to AP2 (the non-root bridge). Yes, its true what others have said about the NRB needing to be connected to the RB, but that just applies to the first NRB in the chain. As long as you can make line of sight connection from AP2 to AP3 (assuming thats what you want to refer it as) you can extend that network. However, if the Root Bridge goes down, loses power, etc, the rest of the chain goes with it.
You should be able to see AP3 as a repeater in the AP2 association list, and like wise in the AP3 list be able to see AP2. If you login to the AP1 RB, you should be able to see AP3 once it becomes active. Just make sure to enable Network Map.