Orbi: True mesh

I live in a four story town house and have bought the Orbi system in order to get better wifi on the top floor. The base is placed in the center of the ground floor which gives great coverage for the ground floor and the first floor. The satellite is placed on the second floor and extend the wifi to the third floor. On the fourth floor the is no wifi coverage I would love to buy a second satellite and place it on the third floor but I understand that this is not possible because it has to be within the reach of the base... I would love if Netgear could add the option for a "true mesh". This is also what I expected when I bought it because it is marketed as a mesh network.

What if you place base unit  on the secound floor and the satelite on the thrid floor would the area covered do the hole house?

If you had a second satelite it could cover the area not covered by the other two maybe.

Not sure of what your home walls and floors are made of and the way wifi will get along with them. 

If the Orbi supported a lan cable between the base and satelite one could get closer to a true mesh setup or at lease cover most of the multi story home.