I have a brand new W7200 system (in AP mode) working fine. I want to add one more node. Not two.  

In an effort to remain completely consistent, I want to add this node to be EXACTLY like the W7200. I don't want to buy another pair.  I want a single node. 

rom my research, I think I have found that the AX3600 and the X68 are the same unit as one single unit of the W7200 Pair.  But I can't be absolutely certain.   Some of the posts say the "software" is different.

Can anyone advise me on the best means of adding one node?  If I HAVE TO, I'll get a second set and only use one of them, but I prefer not to due to pricing. 

Thank you.