Nav Meshes/Random Navigation

Hi.
What I would like to do is have a small rectangular area where ai will pick a random location and goto it. and other ai will try to get into the area. If you did not understand that I will explain it in another way. I lets say I have two Nav Meshes, one for a certain ai(a) and a small rectangular one for another ai(b). Ai “a” are trying to get into the area where ai “b” randomly navigate.

I was also having trouble getting ai to randomly navigate, I managed to get the ai to randomly navigate, but the ai always pick a spot extremely close to themselves.
I would like to make something like this: Unreal Engine 4 Tutorial : AI Navigation - Chase and Roam (AI pt1) - YouTube but in 4.10.

I hope you understand what I am trying to ask, if you could give an answer, that would be awesome, thanks.