I think it will depend on engineer or what they are told by there managers....
But thew official stance is that multi room (360 mini's) aren't being installed currently to avoid unnecessary venturing into personal areas of homes,.
So its likely that the engineer will only install the first TV box and any change that need doing to the hub.
The engineer may also not come into your home and may do the required tests from the outside of property and then instruct you on how to install services yourself through a window.
I had to do my own Sky TV install yesterday yesterday.