Hi 
I currently have a 2866 and a ap903 running in a mesh all is good 

I recently was gifted a 2862 which I don't really have any use for currently, I was just wondering if it's possible to add it as a mesh node to the existing mesh ? 

I took a quick look after booting up the 2862 and I cant see a way to make it a mesh node seems to just be a mesh root so it may be that it can be a wireless node